Information Systems Management Tools: An Application of Bibliometrics to CSR in the Tourism Sector

: Increasingly, the literature highlights the importance of implementing and developing socially responsible behaviours by all stakeholders in the tourism sector. This paper describes the evolution of research on social responsibility in the tourism sector until July 2020. We compiled a database of 846 articles focused on the ﬁeld and published in academic journals in the ISI WoS database. Bibliometric methods and techniques were used to describe the evolution of scientiﬁc activity, countries and active institutions, most productive authors, most relevant sources, most inﬂuential documents, trend topics, and social structure researched. This determined the state of the art and described the evolution of the literature in this ﬁeld, and will help scholars reﬁne existing and initiate new research agendas. A total of 846 papers were identiﬁed and the results showed an upward trend in scientiﬁc production relating corporate social responsibility (CSR) to tourism. Based on these analyses, possible forms of future research are proposed to advance towards the consolidation of this scientiﬁc discipline.


Introduction
At present, society perceives companies only from a financial perspective. Changes brought about by the environment, increased globalisation of markets, greater social repercussions, increased contribution of companies to community development through wealth creation, as well as other factors, such as the necessity to incorporate good governance practices or carry out socially responsible investments, have motivated organisations to adopt changes in their management employing the implementation of socially responsible practices [1]. Despite this, the scientific community has not yet reached a unanimous definition of the concept of corporate social responsibility (CSR), a situation that is justified, on the one hand, because the approaches vary greatly [2], and on the other, because of the ethical and moral variables involved in establishing what activities should be defined as "sufficient" to consider a company socially responsible. There are therefore multiple definitions of CSR (seeČinčalová and Prokop [3]). In fact,Činčalová and Prokop [3] analyzed 100 definitions of the term "Corporate Social Responsibility", reaching the conclusion that the most frequent words used by authors and even key institutions to define it are: voluntary (83%), stakeholders (82%), social (71%), integration (65%), and economic (63%).
One of the most important economic sectors with significant rates of growth in the last years is tourism. Even though this year, because of the global coronavirus pandemic, the situation in the tourism sector is not at its best, tourism has always been a growth industry. Specifically, according to the Synthetic Index of the Spanish Tourist GDP (ISTE) (Available at: http://www.exceltur.org/indicesintetico-del-pib-turistico-espanol-iste/ (consulted 10 September 2020)), the tourist gross domestic product in Spain grew to a rate of 1.5% during the year 2019. These data show that the behaviour of the companies that form this sector significantly influences the development of a better, more equitable, and more sustainable society, thus contributing to its overall well-being [4]. In its magnitude, tourism is a sector capable of generating social change, since it can alleviate problems such as unemployment and unequal opportunity and impel the creation of social value [5]. In this context, according to Medrado and Jackson [6], generally, hospitality companies tend to invest more in environmental initiatives concerning other economic sectors and worry less about environmental issues, such as the carbon footprint.
Based on the above, it is not surprising that there are more and more papers in the literature within the field of tourism that study the influence, involvement, development, or incidence of social responsibility in this sector [7]. However, to follow trends and to create an agenda for new practices or research topics, scholars, professionals, managers, and editors should understand the progress or level of interest in the discipline [8]. In this sense, we echo the mirror theory proposed by Ramos-Rodríguez and Ruiz Navarro [9], which determines that once a scientific discipline has reached a certain degree of maturity, it is essential that its scholars turn their attention to the literature generated by its scientific community. It, therefore, seems necessary to make a quantitative analysis of published material [10]. This is why bibliometric analysis is being increasingly used to map the structure and development of scientific fields or disciplines to assess the evolution of specific disciplines [11].
Although there are numerous and very recent bibliometric analyses within the tourism sector [12][13][14][15][16], indeed, very few studies have used bibliometric analysis to examine leading trends in terms of impact, leading journals, papers, topics, authors, institutions, and countries within the scope of social responsibility in the tourism sector (some exceptions are: Zanfardini et al. [17], Garrigos-Simon et al. [18], and Niñerola et al. [19]). Despite the existence of these publications, the work of Zanfardini et al. [17] made the only epistemological analysis of the evolution of CSR research in the tourism context during 20 years . It focused its study on the prominent journals in the field without taking into account a complete database. On the other hand, the works of Garrigos-Simon et al. [18] and Niñerola et al. [19] focused mainly on the relationship between sustainability and tourism. In this context, we cannot forget that although sustainability and social responsibility are closely related concepts, they do not cover the same aspects [20].
In this sense, in an ample attempt to expand on the literature and show a more realistic state of affairs, based on the importance for the tourism sector of developing socially responsible practices [21] and, therefore, on the need to analyse patterns and trends in research in this field [17], this paper aims to study the social structure, as well as different metrics related to journals, authors, and documents within this field. The analysis and graphical presentations are relevant, as they can help researchers and practitioners better understand the state of the art of social responsibility in the tourism field.
The objective of the present work is to conduct a thorough review of the scientific production of articles on corporate social responsibility (CSR) and tourism using a bibliometric analysis, a methodology that has proliferated in the last decades (in this regard, interest in bibliometric research has increased as a result of the improvement in electronic repositories of academic publications and access through a greater number of databases [22]) [23,24]. Essentially, we tried to provide answers to the following questions: -How has the literature evolved? -In which journals are these articles published? -What countries show a more significant concern for this type of research? -Who are the most productive authors? -Which are the most influential documents? -How are the international relations of scientific production in this field? This research proceeds as follows. First, we describe the origin of the data, the methodology, and the analytic procedure. Second, we show the results. Third, we present our conclusions and discuss their implications and limitations. As well, we identify the main directions in which future research may advance.

Materials and Methods
Based on the contributions of Pritchard [25], bibliometrics is the science that studies the nature and course of discipline using the calculation and analysis of the different facets of written communication. In contrast, the bibliometric methodology handles the quantitative analysis of individual variables present in a published text, approaching the situation scientifically at any given time: problems that dominate, most relevant authors, and underlying social and intellectual structure in that field. In this regard, Flores et al. [26] considered it as "a tool that allows you to develop a set of indicators referred specifically to the scientific production of a discipline, providing, in this way, a base of discussion to consider the degree of consolidation and development of the same". Bibliometric analysis is a quantitative study of literature and can provide evolutionary models of science, technology, and scholarship [27].
The exact and correct application of the bibliometric methodology to the set of works that conform to the research conducted on a particular subject of study requires the examination of the main variables relating to the bibliometric research. Following the proposals exhibited in the literature ( [24,26,28] among others), the selection of the leading indices to analyse in the bibliometric study of any area of knowledge can revolve around the following items [29,30]: The research data used in this paper were downloaded from the WoS Core Collection database, which comprises several sub-databases. We concentrated on data provided by the WoS, which only includes the most influential journals with the highest standards [31], following previous studies [18]. Also, it focuses on the academic and scientific production of the areas associated with the applied social sciences, besides incorporating bibliometric and citation analysis tools, aligned with the use of bibliometric procedures [32].
The bibliometric data were analysed mainly using the software Biblioshiny for Biblometrix [33], considered in recent years to be one of the most useful and complete tools for this type of analysis [34]. To select the research to be evaluated, we retrieved all the papers that used the keywords "social responsibility", "corporate social responsibility", "CSR", "hospitality", "tourism", and "tourist" simultaneously. They were searched in topics, which permitted locating the terms in the titles, keywords, and abstracts in the articles. The population included all papers up to 31 July 2020, and a total of 846 articles were obtained.

Results
The results obtained were published between 1994 and 2020. The sample consisted of 846 articles published in 354 different sources, mostly journals. Of the works found, 752 were research articles, 58 book chapters, 31 early access, and five proceedings papers. The documents content included 2527 author's keywords. A total of 1834 authors were identified and had published an average of 0.461 articles.
We carried out five analyses on the results found in this work. Firstly, the evolution of literature during the period studied was studied. Secondly, the authors who related tourism with CSR were analysed. The third part analysed the sources that published on our topic. Next, in fourth place, we analysed the documents. Finally, we studied the social structure of the literature obtained.

Trends
As shown above, the role that companies in the tourism sector play in the economy is increasingly important. In Figure 1, where the distribution per year of publications related to our study is shown, it is denoted that the results obtained showed a timid incursion of the first works in the last decade of the previous century. Thus, the early four investigations published in WoS that relate CSR to tourism appeared in 1994. From then until 2006, few annual papers were published in the referenced database, and there were even years in which none was published. However, from 2007 onwards, an upward trend in articles continued year after year, with two critical moments in the progress of work. The first was in 2014, with 67 papers published, representing an advance of more than a third over the previous year. This was because, among other things, of the recent concern about climate change and the increasing demand on the part of the tourist for the involvement of tourism companies in matters of social responsibility. The current tourist, without a doubt, is more sensitised to the environment that surrounds him or her, which leads to considering social, environmental, or ethical aspects in the selection processes of products and brands (a phenomenon known as "responsible consumption"). On the other hand, the increase in publications coincided with the end of the global crisis that began in 2008. To meet the expectations of stakeholders, companies now felt the need to be transparent and more socially responsible.

Trends
As shown above, the role that companies in the tourism sector play in the economy is increasingly important. In Figure 1, where the distribution per year of publications related to our study is shown, it is denoted that the results obtained showed a timid incursion of the first works in the last decade of the previous century. Thus, the early four investigations published in WoS that relate CSR to tourism appeared in 1994. From then until 2006, few annual papers were published in the referenced database, and there were even years in which none was published. However, from 2007 onwards, an upward trend in articles continued year after year, with two critical moments in the progress of work. The first was in 2014, with 67 papers published, representing an advance of more than a third over the previous year. This was because, among other things, of the recent concern about climate change and the increasing demand on the part of the tourist for the involvement of tourism companies in matters of social responsibility. The current tourist, without a doubt, is more sensitised to the environment that surrounds him or her, which leads to considering social, environmental, or ethical aspects in the selection processes of products and brands (a phenomenon known as "responsible consumption"). On the other hand, the increase in publications coincided with the end of the global crisis that began in 2008. To meet the expectations of stakeholders, companies now felt the need to be transparent and more socially responsible.
The second significant increase in publications occurred in 2018, when the number of articles reached 100-113, exactly-which was 24 more than in 2017. In the last year of our study, 148 papers were published, making it the year with the highest production of the entire series. In general, as can be seen in Figure 1, the trend is upwards, and every year research into this topic increases considerably, with the annual growth rate at 13.9%.

Most Relevant Authors
The influence an author can have in a given area of knowledge is measured by the number of citations he or she receives for their work. The total number of citations allows for the rapid identification of the most relevant authors in a given field [35]. Since the beginning, many researchers have related tourism with CSR. In our database, we found 1834 authors who related both fields of knowledge between 1994 and 2020. Among them, there were 163 authors of single-authored documents and 1671 authors of multi-authored papers. To identify the most relevant authors, Table  1 shows the ranking of those 36 who received more than 100 citations in WoS. Among them, Font The second significant increase in publications occurred in 2018, when the number of articles reached 100-113, exactly-which was 24 more than in 2017. In the last year of our study, 148 papers were published, making it the year with the highest production of the entire series. In general, as can be seen in Figure 1, the trend is upwards, and every year research into this topic increases considerably, with the annual growth rate at 13.9%.

Most Relevant Authors
The influence an author can have in a given area of knowledge is measured by the number of citations he or she receives for their work. The total number of citations allows for the rapid Sustainability 2020, 12, 8697 5 of 20 identification of the most relevant authors in a given field [35]. Since the beginning, many researchers have related tourism with CSR. In our database, we found 1834 authors who related both fields of knowledge between 1994 and 2020. Among them, there were 163 authors of single-authored documents and 1671 authors of multi-authored papers. To identify the most relevant authors, Table 1 shows the ranking of those 36 who received more than 100 citations in WoS. Among them, Font stood out clearly as the author who obtained the most citations (593) and, at the same time, published the most works (18). However, he was not the most influential author with his work as he only received an average of 33 citations per paper. From this last point of view, we highlighted Noue, who with only two articles achieved a total of 271 citations. We should also mention authors who have achieved more than 100 citations with a single paper, among them Baris and Erdogan, with 153 citations each. In this way, Table 1 shows, in addition to the number of publications and citations of each author, the average citation obtained by each paper. H-index is an indicator to measure the impact of researchers. The score of this indicator quantifies the individual scientific output of each author, comparing papers and citations. The higher the H-index, the more significant the impact of the researcher [36]. In this sense, the author with the highest H-index was Font (see Table 1).

Lotka's Law
Lotka's law is a bibliometric index used primarily to find out the distribution of publications within a given scientific community in a given field [37]. It is also called "the inverse square law of scientific productivity" [38]. When Lotka's law is applied, it is logical that it is used for authors with different research capacities in a given area, which is why the distribution is usually not proportional [39]. This was what happened in this paper. As can be seen in Table 2, 87.6% of the authors, a total of 1607, had published only one article relating tourism to social responsibility. At the other extreme, we observed the most productive authors. Thus we had Font, X., as the researcher who produced the most papers in the area studied, with 18 articles published. The second author was Su, L.J., who published 15 works. In many analyses of academic productivity through Lotka's law ( [40][41][42]), the group of authors with the highest productivity and most significant influence is composed of few researchers. The same was observed in our work. There were only 13 academics who had published more than five articles and only two with 15 or more. Conversely, most of the authors published only one paper relating tourism to social responsibility. Of course, with Lotka's law, we could do only a quantitative study, so the quality of the documents and the authors could not be measured with this index [39].  Table 3 shows the most relevant countries in the production of scientific articles that related social responsibility to tourism. This table shows Spain as the country that contributed the most to the publication of the largest number of articles, precisely 202 papers. In addition, Table 4 shows that among the universities in the world that published the most on the subject we were analysing, there were six Spanish universities. At the top of the ranking, three Spanish universities led. In first place was the University of Malaga with 18 papers, followed by the University of La Laguna and the University of Seville with 15 articles each. The country with the second most documents was the USA. However, in the ranking of the 16 universities with the most papers, there were no American universities. This means that, unlike Spain, there were no universities in the USA that specialised in this area. Thus, its scientific production was dispersed among universities throughout the country, with none of them standing out. The University of Surrey, located in southern England, was the one with the most affiliated authors, who wrote 21 works out of all the scientific production in our studied field.

Most Relevant Sources
Another aspect that we considered in carrying out a study of this nature was the analysis of the journals in which these works were published. One of the main problems in gathering literature was the specialisation of journals. This was why we denoted a broad spectrum of journals, which was not limited to specific publications in this field. In this sense, Vázquez-Carrasco and López-Pérez [43] suggested that one of the main limitations or difficulties in accessing the works related to CSR is the wide variety of journals in which they are published.
Our study showed that the 846 papers found were accepted by 354 different sources, demonstrating the wide variety of publications that included CSR research in the tourism sector. Furthermore, the multidisciplinary nature of the research area aroused interest in different fields of knowledge, not only in tourism journals or CSR journals. There were five publications with 20 or more papers, representing 20.69% of all scientific production studied. The journal that published the most articles was the Journal of Sustainable Tourism with 55 papers. In second place was Sustainability, with 43 papers published. Tourist Management was the journal that published the third most articles in our field of study, a total of 32 papers. Finally, the fourth and fifth journals were International Journal of Contemporary Hospitality Management and International Journal of Hospitality Management, with 25 and 20 papers, respectively. This showed the great interest of these journals in publishing articles that related to CSR Sustainability 2020, 12, 8697 8 of 20 and tourism. On the opposite side, there were a wide variety of publications that accepted only one paper on our subject. In total, there were 248 papers, which represented 29.31% of the total production.

Bradford's Law
Bradford's law of scattering is one of the most regularly used laws in bibliometrics. It shows a quantitative relationship between journals and scientific articles contained in a bibliography on a given topic. This law attempts to show that in the production of journal articles there is a highly unequal distribution where most items are concentrated in a small population of journals. In contrast, a small proportion of articles are scattered over a high number of articles. Journals can be divided into three groups or clusters by the number of documents. Thus, the proportion of the number of journals in each group would correspond to formulation 1:a:a 2 . Through this process, in each area with the same number of articles, the number of journals grows exponentially [44].
In this research, we differentiated three clusters to bring together scientific production in the field studied. In this way, we detected a first cluster composed of 14 journals, in which 284 papers were published (see Table 5). To publish the same number of articles (284), we identified 75 journals in the second cluster. This meant that to publish the same number of articles, we found 59 more journals, demonstrating the dispersion of production. Finally, the third cluster was made up of 262 journals in which 278 articles were published. Thus, in the first cluster, there was a higher concentration of journals that published more articles. It had an average of 17.75 papers per journal. The Journal of Sustainable Tourism stood out as the journal that accepted the most papers, precisely 55, that studied social responsibility with tourism. Second was Sustainability, with 43 articles published. Third was Tourism Management with 32 publications. In the second cluster, the average number of papers per journal was reduced to 4.81. The third cluster showed an average of 1.06 articles per journal.
The analysis of the results meant that our research proved Bradford's law. In this way, we can state that the distribution of scientific production in this field of study is unequal. Therefore, there was a big concentration in the first 14 journals, from which the dispersion increased. Of the 846 journals, 245, which represented 28.85%, only published one article relating to CSR and tourism.  Figure 2 shows the evolution from 1994 to 2020 of the publications in the five leading journals: Journal of Sustainable Tourism, Sustainability, Tourism Management, International Journal of Contemporary Hospitality Management and International Journal of Hospitality Management. Looking at the graph, we can indicate that in the first years there were no publications in these journals. The first of them to publish a paper linking CSR and tourism was Tourist Management in 2007, so in the previous 13 years none of the top journals published on our subject. According to the graph, in 2010, four of the five journals had already published some work. The last source to publish was Sustainability, which began in 2013, and reached its highest number of papers in 2019, publishing a total of 23, making it the second journal to publish work in this field. 2019 was the year in which most articles relating to CSR were published in the tourism sector. However, it is also worth mentioning that in 2018 there was a significant peak in the number of papers published in these five journals.
Sustainability 2020, 12, x FOR PEER REVIEW 9 of 20 can indicate that in the first years there were no publications in these journals. The first of them to publish a paper linking CSR and tourism was Tourist Management in 2007, so in the previous 13 years none of the top journals published on our subject. According to the graph, in 2010, four of the five journals had already published some work. The last source to publish was Sustainability, which began in 2013, and reached its highest number of papers in 2019, publishing a total of 23, making it the second journal to publish work in this field. 2019 was the year in which most articles relating to CSR were published in the tourism sector. However, it is also worth mentioning that in 2018 there was a significant peak in the number of papers published in these five journals.

Most Globally Cited Documents
The relevance of academic documents can be shown through the analysis of the number of citations that their published articles achieved. As well as the popularity and influence of the paper within a research field [18], the analysis of our results provided a total of 846 papers written in the area of tourism and CSR. The total number of citations obtained in those 846 papers was 8824 in WoS. To identify the most influential documents in the field of CSR in the tourism sector, we based our analysis on the top 10 papers with the most citations. The number of citations reveals the quality of the document. Table 6 illustrates the most outstanding papers and their characteristics.

Most Globally Cited Documents
The relevance of academic documents can be shown through the analysis of the number of citations that their published articles achieved. As well as the popularity and influence of the paper within a research field [18], the analysis of our results provided a total of 846 papers written in the area of tourism and CSR. The total number of citations obtained in those 846 papers was 8824 in WoS. To identify the most influential documents in the field of CSR in the tourism sector, we based our analysis on the top 10 papers with the most citations. The number of citations reveals the quality of the document. Table 6 illustrates the most outstanding papers and their characteristics. The article by Inoue [45] ranked first in the number of citations in the area of tourism and CSR. Since its publication in 2011, it has been cited on 247 occasions and therefore had 2.8% of the total number of citations obtained by the papers in this study. It also led in the number of citations per year (24.70). This article studied the relationship of CSR through five dimensions, with the financial performance of companies in the tourism sector. The five dimensions, based on the company's voluntary activities, were of interest to stakeholders. These dimensions proposed by the authors were: (1) employee relations, (2) product quality, (3) community relations, (4) environmental issues, and (5) diversity. The results indicated that each of these dimensions had a direct influence on the profits of the companies studied. The second most cited work was Erdogan and Baris [46] with a total of 153 citations since 2007, the year of its publication. This paper developed its research in hotels in Ankara (Turkia). The results showed that policies and practices in the city's hotel sector generally lacked attributes relevant to environmental protection and conservation. Moreover, hotel managers mostly lacked the environmental knowledge and interest necessary to meet the primary objectives of social and environmental responsibility. However, on this occasion and despite being the second paper in the ranking of the most citations, it was not the second one for the most citations per year, but rather the sixth. There was one paper that did not belong to the top 10 that had more citations per year (11.67). This was the article by Serra-Cantalops et al. [55], which in only two years achieved enough citations to rank fifth in citations per year. The paper by Sin [47] ranked in the third position in number of citations (131) and fourth in citations per year (11.91). This work referred to the impact of solidarity tourism on host communities. The research was carried out in Cambodia, through 14 personal interviews with residents. The results indicated positive opinions but also negative ones. The rest of the papers were diverse, both in terms of authors and content.

Most Frequent Words
This analysis identified the most frequent words used by authors publishing in the field of tourism and CSR. This identification of most frequent words was made by the number of occurrences in the documents' keywords, just below the abstract. The aim was to discover the most relevant topics within the field of research we were analysing. Biblioshiny revealed that there were 2152 keywords. Table 7 shows the ten most frequently used keywords. "Tourism" was the word used most often, precisely 363 times. Next was "social", which appeared in the second position, in 240 different papers. The third word was "responsibility", which appeared 213 times. In general, of the first 10 words, five (tourism, corporate, industry, management, and hospitality) were more related to tourism. The other five words (social, responsibility, sustainable, sustainability, and development) were more associated with CSR. To understand the use of the keywords used with tourism and CSR, the keywords in the cloud allowed a mental imagery [56]. Figure 3, shows the word cloud generated by Biblioshiny of the Bibliometrix software. The word cloud highlights the aspects related to tourism and CSR. The author's keywords are selected in the graphic parameters. The most significant advantage of being able to choose these keywords is to highlight the main topics and trends in research [57]. As the figure shows, tourism, management, performance, and CSR were the main keywords used in the documents produced.
shows the word cloud generated by Biblioshiny of the Bibliometrix software. The word cloud highlights the aspects related to tourism and CSR. The author's keywords are selected in the graphic parameters. The most significant advantage of being able to choose these keywords is to highlight the main topics and trends in research [57]. As the figure shows, tourism, management, performance, and CSR were the main keywords used in the documents produced.

Trend Topics
Perhaps because of the boom in research in this field of study in the last years, we can appreciate that the analysis covered multiple directions, due to the lack of an established paradigm. Based on keyword analysis and the word cloud, we found 32 different topics, although they were intimately related. Table 8 represents the top 10 search trends. They were nearly equal in importance, but the three best topics were framework, loyalty, and consumers. Respectively, they had frequencies of 27, 25 and 22.

Social Structure
His or her social identity fundamentally shapes a person's self-concept. Social identity is defined as the knowledge that an individual possesses by belonging to certain social groups, together with the emotional and value significance of being a member of those groups. The fundamental idea of the theory of social identity is that our belonging to groups and our relationships with them largely determines who we are as individuals. In other words, this belonging influences our identity [58]. Different approaches can be used in organisations such as marketing, human resources, or CSR. There are also various sectors such as health, banking, or the tourism sector. Through these different groups, they build their own social identities, which are studied in the academic world through the social structure [59]. The analysis that academics make of this social structure helps managers to find solutions within an industry, using the existing resources in that industry. In the academic world, the social structure constructs the identity of the different disciplines by employing three methods: (1) collaboration in scientific studies, (2) existence and impact of related associations, and (3) scientific journals [60]. In this paper, we analysed the first of these methods. We investigated collaboration in scientific studies, through collaboration between countries, institutions, and authors.

Country Collaboration Network
Collaboration networks between countries are produced by the co-authorship of papers by authors from different countries. Figure 4 graphically shows these networks of co-occurrences between countries in the literature relating CSR to the tourism sector. The size of the circle indicates the number of occurrences of the papers; the larger the node, the more co-authorships the country shows. The strength of the collaboration between countries is represented by the distance between the circles in individual pairs. Thus, the closer the circles are, the more intense the collaboration.  Similarly, the farther away the collaboration is, the weaker it is. The different colours of the circles are assigned to the individual fields of cooperation. The total strength of a link is shown by the number of papers in which the authors of a given publication represent the two countries involved in that link [34].
When analysing the networks created between the different countries, we found 88 countries represented by authors collaborating in tourism and CSR research. United Kingdom, Australia, USA, China, and Spain were the countries that collaborated most internationally. USA and China had a close collaboration. They both worked on the same subject, as a result they have the same colour. The other cluster to highlight is the one formed by United Kingdom and Spain. These two countries also agreed on the subject matter. In a third cluster, the green one, Australia stands out (see Figure 4).
We also analysed networks of collaboration between countries according to where the first author of the publication belonged. Thus, the country that published most with authors from other nations was China, with 61 papers. The greatest total link strength was with authors from the USA. In total, we found 24 articles on which China and the USA collaborated, the first author being a Chinese researcher. Secondly, United Kingdom published 60 papers. Its strongest link was with Spanish authors, with whom it collaborated on 14 occasions. It was with this country that there was the most significant collaboration. Although it had fewer links with other countries, it was followed by the USA, South Africa, and New Zealand, with 26, 25, and 21 papers, respectively. It is curious that, as Spain had the most articles on tourism and CSR, only 14 articles were found in which it collaborated internationally and in which a Spanish researcher was the first author. However, it is also worth noting that there were countries that had an important scientific production but that collaborated little internationally. This was the case of Brazil, which, being the eighth country in terms Similarly, the farther away the collaboration is, the weaker it is. The different colours of the circles are assigned to the individual fields of cooperation. The total strength of a link is shown by the number of papers in which the authors of a given publication represent the two countries involved in that link [34].
When analysing the networks created between the different countries, we found 88 countries represented by authors collaborating in tourism and CSR research. United Kingdom, Australia, USA, China, and Spain were the countries that collaborated most internationally. USA and China had a close collaboration. They both worked on the same subject, as a result they have the same colour. The other cluster to highlight is the one formed by United Kingdom and Spain. These two countries also agreed on the subject matter. In a third cluster, the green one, Australia stands out (see Figure 4).
We also analysed networks of collaboration between countries according to where the first author of the publication belonged. Thus, the country that published most with authors from other nations was China, with 61 papers. The greatest total link strength was with authors from the USA. In total, we found 24 articles on which China and the USA collaborated, the first author being a Chinese researcher. Secondly, United Kingdom published 60 papers. Its strongest link was with Spanish authors, with whom it collaborated on 14 occasions. It was with this country that there was the most significant collaboration. Although it had fewer links with other countries, it was followed by the USA, South Africa, and New Zealand, with 26, 25, and 21 papers, respectively. It is curious that, as Spain had the most articles on tourism and CSR, only 14 articles were found in which it collaborated internationally and in which a Spanish researcher was the first author. However, it is also worth noting that there were countries that had an important scientific production but that collaborated little internationally. This was the case of Brazil, which, being the eighth country in terms of the production of work on CSR and tourism, with 44 publications, only had five links for collaboration. Moreover, these links were with different countries, specifically, one with Belarus, another with Germany, two with Portugal, and one with Spain. This indicated that it did not have stable relationships to publish in this field of knowledge.

Institution and Author Collaboration Networks
Bibliometric analysis, as we know, highlights the so-called co-authorship. This analysis helps to determine the structure of collaborative research networks in a specific field. This includes the self-organising behaviour of the research areas. The nodes reveal the most influential institutions, and the thickness and distance between nodes indicate the degree of collaboration [18]. Figure 5 shows the most influential institutions that have researched tourism and CSR with colleagues from other countries. Thus, it is possible to observe four significant clusters. The first, in green, groups the University of Surrey (England), as the strongest collaborating institution in this group, with Sun Yat-sen University (China). In orange, the second cluster highlights the University of Johannesburg, which collaborated with Washington State University. The third cluster, in red, has as its central institution the Cent South University located in Changsha in the south-central of China. The University of Wisconsin (USA) is the most collaborative institution in this red cluster. The last interesting cluster to be highlighted is the one shown in Figure 5 in brown colour. Jinwen University of Science and Technology (Taiwan) forms this group of institutions with the largest node. It often collaborated with the National Taiwan Normal University and MingDao University (Taiwan).  In the same way, we can see Figure 6. This figure shows different clusters formed by authors who collaborated internationally. Among them, two stand out, the purple and the red. Three authors form the purple cluster. The primary author is Xavier Font from the University of Surrey, who, as mentioned above, is the author with the most publications in this field. Together with him, a robust collaboration network was created with Lluís Garay (Universitat Oberta de Catalunya). The other set to highlight is the red one. Lujun Su, who is an affiliate to the Business School Central South University (China), is the author of that group with the highest scientific production. Although he also collaborated with Xiaohong Chen, from the same university, his principal connection was with Scott R. Swanson, professor of marketing at the University of Wisconsin, both authors having published together on 15 occasions in recent years. In the same way, we can see Figure 6. This figure shows different clusters formed by authors who collaborated internationally. Among them, two stand out, the purple and the red. Three authors form the purple cluster. The primary author is Xavier Font from the University of Surrey, who, as mentioned above, is the author with the most publications in this field. Together with him, a robust collaboration network was created with Lluís Garay (Universitat Oberta de Catalunya). The other set to highlight is the red one. Lujun Su, who is an affiliate to the Business School Central South University (China), is the author of that group with the highest scientific production. Although he also collaborated with Xiaohong Chen, from the same university, his principal connection was with Scott R. Swanson, professor of marketing at the University of Wisconsin, both authors having published together on 15 occasions in recent years. who collaborated internationally. Among them, two stand out, the purple and the red. Three authors form the purple cluster. The primary author is Xavier Font from the University of Surrey, who, as mentioned above, is the author with the most publications in this field. Together with him, a robust collaboration network was created with Lluís Garay (Universitat Oberta de Catalunya). The other set to highlight is the red one. Lujun Su, who is an affiliate to the Business School Central South University (China), is the author of that group with the highest scientific production. Although he also collaborated with Xiaohong Chen, from the same university, his principal connection was with Scott R. Swanson, professor of marketing at the University of Wisconsin, both authors having published together on 15 occasions in recent years.

Discussion and Conclusions
Whereas the term CSR can seem relatively new in the business world, academic literature reveals that the evolution of the concept in itself has taken place over several decades. Although the majority of the empirical research on CSR focuses on large companies, our study shows an upward trend in the publication of articles centring on the tourism sector in prestigious journals within the field of business management and business ethics [61]. This research studied the relevance of the academic literature that related CSR to tourism. In Table 9, we present the answers to the main research questions made in the introduction. As a result of the absence of studies in the literature and the importance of bibliometric approaches, we developed a bibliometric study on all the articles found during a 26-year period (1994-2020). This period covered all the published research on social responsibility in the tourism sector, and it helped to have a large number of documents that allowed having a complete view of this field of research. This is an essential contribution of our paper since other publications have studied other variables or shorter periods of time.
According to the analysis of this study in the ISI WoS database, several findings are reported. Firstly, the literature relating to tourism and CSR is still growing. Moreover, there has been a considerable increase from 2007 onwards, especially in the last two years. These results are in line with those presented by Garrigos-Simon et al. [18] in their study on sustainability and CSR, showing that moral, ethical, and environmental issues are becoming an integral component of tourism policy and strategy.
Second, currently, CSR has been consolidated within the organisation, impacting on different areas, but especially on the business strategy of tourism companies [19]. The attention that CSR is receiving in the tourism sector does not correspond to well-distributed scientific production throughout the world, although many countries already publish in this field. The leading research country that has written the most tourism and CSR papers is located in Spain, followed by the USA and China. Similar results were found in Herrera-Madueño et al. [62]. Even though the study was on CSR and SMEs, both findings seem to show the interest and development of research and implementation of these practices in this country. However, Spain is not the country that collaborates most internationally with other authors. In this regard, the UK is the first country, with co-authorships with foreign colleagues. Thirdly, scientific production related to tourism and CSR has been widely applied in trend topics such as frameworks, loyalty, and consumers.
On the other hand, the quantitative analysis of the 846 documents served to draw several interesting conclusions. First, it was proved that the frequency indexes of author productivity distribution followed Lotka's law. As occurred in Serrano et al. [16], there was an unequal distribution of productivity among authors. Most of the authors relating tourism and CSR published a single document, accounting for 87.6% of the total number of authors. Therefore, the group with the highest productivity and influence consisted of a small number of researchers. In contrast, there were many authors with low production. In this sense, a few academics have written a significant number of papers. Font was the author who has published the most, with 18 articles to his credit. Of course, Lotka's law only allows a quantitative analysis, which does not ensure the quality of the literature analysed.
Second, according to Bradford's law, the three-zone ratio was approximately equal to 1:3:3 2 , which meant the data were consistent with Bradford's law [38]. In this way, 354 sources were identified in the field studied. In the first area, the first third of articles were published in only 16 journals. Among these journals, the largest number of papers was written for the Journal of Sustainable Tourism, followed by Sustainability. Both were the most published journals in the field of tourism and CSR. To publish the second third, 75 journals were needed. The last 278 papers were published in 262 journals, almost one in each journal. The above data proved Bradford's law. These findings were in line with Durán et al.'s [63] bibliometric analysis of publications on wine tourism in the databases Scopus and WoS. It was also interesting to note that in the first 13 years of our study, no CSR and tourism journals were published in any of the top five journals. It was Tourist Management, the third in the ranking, that published the first article in 2007. This large number of sources from further research indicated that the topic was multidisciplinary. It also represented an opportunity for researchers to find an outlet for their work. On the other hand, examinations of citations indicated that the most influential and most cited document in our field of research was one written by Inoue and Lee [45]. It received an average of 24.70 citations per year, which, since 2011, has totalled 247 citations received.
Collaboration analysis indicated that the authors who worked together the most in articles were Xavier Font from the University of Surrey and Lluís Garay from the Universitat Oberta de Catalunya. In this way, they created a stable relationship between the two universities and a working relationship between England and Spain. Another interesting active link was between Lujun Su, Xiaohong Chen, and Scott R. Swanson. The first two authors are affiliated with the Central South University Business School and the third works at the University of Wisconsin. This showed the interaction between China and the USA. Finally, the co-authorship analysis revealed the prevalence of two countries (USA and UK) leading the main clusters. The study showed that the top two institutions that had international collaboration networks were the University of Surrey and the University of Johannesburg. It also revealed that Spanish universities did not have many contacts with international colleges despite being the country that published the most.
Our study contributes to both theory and practice. This research on the distribution of production in tourism and CSR contributes to informing researchers and academics of current issues and the development of the field under investigation; to allowing researchers to go deeper into the area as our analysis allowed to identify the most relevant authors, the best journals, or the most famous documents; as well as to identifying trend topics. This makes it possible for academics to identify trends in research in this area. On the other hand, this work will also be beneficial for those researchers and organisations related to documentation services or social science library services. Our investigation permits to know what topics and areas of research within this field should be promoted or what kind of journals should be purchased, which are useful in future lines of research.
However, the present study shows some limitations that must be mentioned. First of all, the group of indicators and bibliometric techniques used for the content analysis of published articles was an issue. It would be interesting to use other data analysis techniques with different objectives that complement this work, as, for example, the method of coappointments [64]. In the same way, one could expand data searches to new search engines, as well as use other terms to search for the resulting articles. Another limitation may be linked to the fact that the study used abstracts and titles instead of full text for the selection of works. However, as already pointed out by Vázquez-Carrasco and López-Pérez [43], although it is necessary to mention certain limitations of the research, it must also be taken into account that the defects of these studies are inherent to bibliometric analysis as a genre.
As a future line of research, and since Vázquez-Carrasco and López-Pérez [43] already did this in their studies, we propose a bibliometric analysis to update the main CSR activities that tourism companies are actually carrying out for their stakeholders. We also suggest an analysis of the main barriers and drivers tourism companies have experienced while implementing CSR. On the other hand, future research could be to extend the analysis with the use of databases such as Scopus or Google Scholar, or other sources that analyse different types of documents or texts in other languages. It would also be interesting in the future to use other software or methodologies that could enrich this work, using other bibliographic methods. Finally, the study can be completed and redefined with a more in-depth analysis of some of the clusters and themes detected in this work. Last, but not least, and taking into account that the pandemic caused by COVID-19 has undoubtedly modified the sector at least temporarily, it will be interesting to carry out a study based on bibliometric tools to highlight and analyse the main themes and implications that management of the crisis has had on the sector at a national and even an international level.