Current Research Trends on Interrelationships of Eco-Innovation and Internationalisation: A Bibliometric Analysis

: In this paper, bibliometric analysis is conducted on eco-innovation and internationalisation, since in the scientiﬁc literature, both research ﬁelds have been considered as being interrelated. Although the adoption of eco-innovation and internationalisation are risky processes, they reduce competitive risk and increase performance in a highly competitive business environment. The main objective of this study is to identify current research trends on the interrelationships of eco-innovations and internationalisation as well as the main areas of knowledge and to provide a general overview of research streams that can be classiﬁed using by papers, authors and journals found in the Web of Science database. In total, 1677 publications published between 1991 and 2020 related to eco-innovations and internationalisation were taken into consideration. For the visualisation of bibliographic material, VOSviewer software was used. These ﬁndings provide valuable insights by revealing the trends and highlighting the possible research streams for future investigations in the ﬁeld of eco-innovations and internationalisation research.


Introduction
The total quantity of scientific research literature on a particular field of study can often be overwhelming (van Nunen et al. 2018) and continues to rise, which makes it difficult for scientists to have a structured overview of important information. Bibliometrics is a valuable tool for a literature analysis that can efficiently reveal the latest advances in a specific field of research (Wang et al. 2014). The worldwide shift towards sustainable development and environmental integrity makes it necessary for companies to take adaptation and risk management actions in order to reduce their environmental impact while developing products and services. There is a solidarity among academics and market professionals regarding the changes needed in current business practices and how these changes affect natural and social environments. Due to the environmental issues and increased focus on sustainability, eco-innovations are gaining more and more attention. This concept has been discussed in the majority of the United Nations (UN) sustainable development goals (SDGs) and thus, to achieve these goals, eco-innovation must be involved, i.e., innovations that reduce environmental and social impacts while causing disruptions and improvements to existing production models (Lopes Santos et al. 2019).
The growing demand from consumers and world-wide regulatory requirements for eco-friendly products and services challenge companies to adopt eco-innovations not only in their domestic markets but also for exporting companies in their foreign markets, making both internationalisation

Eco-Innovation
Over the last three decades, the eco-innovation concept has been embedded in most sustainability research documents. Although the term was defined in 1996, most eco-innovation research publications have been published after 2009 (Kuo and Smith 2018). Eco-innovation (sometimes defined as environmental or green innovation) is usually defined as innovation that results in a reduction of environmental impact. Furthermore, as compared to traditional forms of innovation, eco-innovation emphasises the companies' mitigation of negative impacts and are associated with environmental benefits (Liao and Tsai 2019). Over the last 30 years, other terms have been used to define the strategy of eco-innovation, such as green innovation, environmental innovation, sustainable innovation, etc. The main methods used to extend beyond traditional forms of innovation over the time emphasise social and environmental impacts, changes of business models that involve the consumption of materials, energy and water (Lopes Santos et al. 2019). Moreover, eco-innovation can be adopted by companies or non-profit organisations at different social, technological, institutional or organisational levels (González-Ruiz et al. 2018). Notably, the definitions of eco-innovation are based on the concept of "traditional innovation with reduction of environmental impact" and reflect regulatory requirements for companies to consider the consequences of their operations (Lopes Santos et al. 2019).
Organisation for Economic Cooperation and Development (OECD) defines eco-innovation as "the implementation of a new or significantly improved product (good or service), or process, a new marketing method, or a new organisational method for business practices, workplace organisation or external relations, that results in a reduction of environmental impact, no matter whether that effect is intended or not and the scope of eco-innovation may go beyond the conventional organisational boundaries and involve broader social arrangements that trigger changes in existing socio-cultural norms and institutional structures". Furthermore, Organisation for Economic Cooperation and Development (OECD) distinguished three main facets of eco-innovation: 1. Targets, such as products, processes (rely on technological development), marketing methods, organisations and institutions (rely on non-technological development). 2. Mechanisms, that involve practice modifications, redesign and new alternatives, or the creation of entirely new practices. 3. Impacts, which defines how the eco-innovation affects environmental conditions. The European Commission grouped 16 indicators into five dimensions determining eco-innovation: inputs, activities, outputs, resource efficiency and socio-economic outcomes (Spaini et al. 2018). Paraschiv et al. (2012) argue that one of the main factors influencing companies' sustainable development is eco-innovation, which plays a key role in achieving global corporate sustainability goals. Hence, eco-innovation is one of the key factors involved in achieving global sustainability objectives and moving industries towards sustainable development, with important potential benefits for innovative companies, industries and even entire economies (Paraschiv et al. 2011). However, the main barrier towards implementing eco-innovation is financial factors and a lack of sufficient resources (Przychodzen and Przychodzen 2015).
In the context of sustainable development, eco-innovations are essential for organisations seeking to align themselves with international concerns related to environmental protection, human rights and the wealth of their employees (Paraschiv et al. 2012). In order to achieve the SDGs, eco-innovation has been proposed as an effective solution to help companies to reduce their negative environmental impacts (Kuo and Smith 2018). In this study, the term "eco-innovation" is in line with UN's SDGs view and emphasises the ecological dimension of these goals.

Internationalisation
Internationalisation is not as new a phenomenon as eco-innovation. As the subject of the research, internationalisation has been developing for more than sixty years (Głodowska et al. 2019); however, the number of scientific publications continues to rise. Though initial studies considered large corporations, later on the discussions have been expanded in the small business context (Korsakienė et al. 2019a). Moreover, internationalisation has been analysed in many scientific disciplines. Thus, various approaches to study the phenomenon were applied stemming from management, economics, entrepreneurship, etc.
The traditional internationalisation approaches such as the Uppsala model (Vahlne and Johanson 2013) defines internationalisation as the process of acquiring, integrating and utilising knowledge and competence in international operations through increased participation in international markets. Meanwhile, new investigations continue to study the phenomenon and define internationalisation as a multi-stage process which also has a curvilinear relationship with a firm's performance (Nguyen et al. 2019). While business, economic and social environments have been changing over time, the different phases and dimensions of internationalisation have been emerging (Deng et al. 2020). Thus, the scholars treat the internationalisation process as encompassing the opportunities for emerging foreign firms to build various relationships (Deng et al. 2020). Moreover, previous investigations in the context of smaller firms disclosed various paths of growth, such as through the improvement of products, expansion of market share through innovation or the expansion of foreign market share through exports i.e., internationalisation (Henley and Song 2019).
Finally, internationalisation is assumed to be a strategic decision through which companies seek increased involvement in global markets and foreign sales. Though scientific discussion on internationalisation has triggered a number of studies, the majority of studies rely on the degree of a company's internationalisation, i.e., the proportion of their export sales to total sales, as a single measurement of internationalisation (Genc et al. 2019;Korsakienė et al. 2019b). Moreover, export performance appears to be the main indicator used to observe internationalisation of the companies, especially in the small business context.

Interrelationships of Eco-Innovations and Internationalisation
The importance of internationalisation and eco-innovations in organisational performance has triggered scientific debates. Apparently, innovation capabilities developed by firms impact strategic behaviour, including their stance towards internationalisation (Mi et al. 2020). Many authors, with evidence from different countries and product groups, emphasise the importance of innovation in order to increase export performance and competitiveness (Priede and Pereira 2015). For instance, investigations performed in Australia revealed that eco-innovation increased international performance (Ratten 2018). The studies revealed that companies that have international operations are more innovative than those do not, highlighting the fact that exporters are significantly more likely to introduce product, process and management innovation (Shearmur et al. 2015). Therefore, organisations must focus on two approaches. First, the companies have to innovate to exploit technological opportunities. Second, the companies have to respond to the changes in demand and lifestyles of consumers (Bossle et al. 2016). In addition, the "green barrier" hinders companies' collaborations with international organisations unless they meet all the necessary ecological regulatory requirements.
While some studies investigated the direct relationship between innovation and internationalisation (Chiarvesio et al. 2015), other studies investigated the mediation effect of eco-innovation. Juniati et al. (2019) argues that eco-innovation has an important mediating effect on the relationship between internationalisation and performance in Malaysian multinational firms. According to the authors, the relationship between internationalisation and eco-innovation enables companies to achieve better performance and competitiveness, and also contributes to their environmental and social improvements. Juniati et al. (2019) suggests that internationalisation is a driving force for companies to learn and implement eco-innovations. Moreover, internationalisation with assimilated eco-innovations enable companies to achieve better performance. Thus, it was confirmed by multiple studies that the companies are encouraged to expand business horizons to achieve cost efficiencies, as well as technological and business function improvements. However, the study only considered large multinational firms and did not take into account other variables, which is the limitation for large multi-national corporation studies (Juniati et al. 2019). Meanwhile, the study performed by Hojnik et al. (2018) investigated 151 Slovenian internationalized companies and revealed that companies which implement a learning process based on internationalisation activities and eco-innovation initiatives improve their economic performance.
The scholars discussing the organisational learning perspective aim to shed light on the relationship between internationalisation and eco-innovation. They argue that when companies export, they gain information on foreign customers' needs and regulatory demands, as well as an improved understanding of foreign markets, partners, competitors and their technological gaps. Knowledge acquisition is one of the key factors affecting the internationalisation and learning process, which lets companies incorporate gained knowledge into firm-level routines and improve their product, process, and organisational innovations. These findings complement the "learning by exporting" stream of research, which suggests that exporters learn from foreign customers and partners by implementing new production technologies and subsequently innovate. Thus, the findings of Hojnik et al. (2018) indicate that eco-innovation adoption and environmental sustainability are significant and comprise the key drivers for serving foreign markets. According to these scholars, internationalisation leads to the adoption of eco-innovation and the relationship between internationalisation and eco-innovation is stronger in medium-sized and large companies, especially in manufacturing companies, that operate in the business-to-consumer market and companies that are ISO14001 accredited. However, the study relied on the self-reported measurements provided by companies' environmental or quality managers, meaning further investigation needs to be done using more direct objective measurements (Hojnik et al. 2018).

Purpose of the Study
While considering the dynamics in economical, ecological and social environments, the research question is formulated as follows: what is the current state of knowledge about the interrelationships between eco-innovations and internationalisation and how it has been investigated? The purpose of this study is to disclose and provide a coherent overview of current research trends on the interrelationships between eco-innovations and internationalisation and to highlight the possible research streams for future investigations. To achieve the objective, we analyse the academic literature by adopting a bibliometric methodology, which offers a systematic and macroscopic overview of current knowledge. Bibliometric analysis is a technique for providing an extensive overview of large amounts of scientific literature in a particular field of research and can be used to evaluate the research trends and cooperation patterns involving authors, journals and countries = (van Nunen et al. 2018). This paper contributes to the literature of eco-innovations and internationalisation by bringing the two together and using their core findings to study the interrelationships between them. The data in this study provides an overview on the research progress achieved in the streams of eco-innovations and internationalisation and it can help both researchers and professionals to identify the most influential authors, journals, countries and research topics.

Materials and Methods
Bibliometric analysis is a valuable tool for studying bibliographic materials by using quantitative methods. The method became very popular for the representation of summarised results of classified bibliography (Cancino et al. 2017). The method includes various steps that must be taken by researchers. These steps are pre-established through the research protocol and all possible sources of error (or bias) that can undermine the relevance of the study are considered (Pedro et al. 2018). The stages included in the research protocol of this study are presented in Figure 1. Moreover, before stage 1, the following research questions were formulated: J. Risk Financial Manag. 2020, 13, x FOR PEER REVIEW 5 of 17 overview of current knowledge. Bibliometric analysis is a technique for providing an extensive overview of large amounts of scientific literature in a particular field of research and can be used to evaluate the research trends and cooperation patterns involving authors, journals and countries = (van Nunen et al. 2018). This paper contributes to the literature of eco-innovations and internationalisation by bringing the two together and using their core findings to study the interrelationships between them. The data in this study provides an overview on the research progress achieved in the streams of eco-innovations and internationalisation and it can help both researchers and professionals to identify the most influential authors, journals, countries and research topics.

Materials and Methods
Bibliometric analysis is a valuable tool for studying bibliographic materials by using quantitative methods. The method became very popular for the representation of summarised results of classified bibliography (Cancino et al. 2017). The method includes various steps that must be taken by researchers. These steps are pre-established through the research protocol and all possible sources of error (or bias) that can undermine the relevance of the study are considered (Pedro et al. 2018). The stages included in the research protocol of this study are presented in Figure 1. Moreover, before stage 1, the following research questions were formulated: RQ1: what is the output and growth trend of publications in the selected streams? RQ2: which are the most influential countries and journals that are impacting the research streams?
RQ3: what is the relationship between internationalisation and eco-innovation and how it is being investigated?

Stage 1: Search Criteria
The first condition for the study was to rely on scientific papers that are investigating ecoinnovation and internationalisation as the main concepts. This condition for the keywords was used for several reasons. Firstly, it aimed to ensure that the scientific literature is within the scope of this paper. Secondly, it aimed to ensure that this study did not divert away from the main research questions. Hence, numerous synonyms were used in conjunction with the main keywords and the initial search string was composed of three parts: the first focused on the ecological part using eco OR ecologic OR environment OR sustainable OR green, the second focused on innovations, using innovation and the last focused on internationalisation part, using internationalisation OR export. No quotation marks were included, however an asterisk was included to extract the synonyms. Notably, the filtering of general noun phrases, such as result, study, paper, etc. was crucial (Van Raan 2014), because these general meaning noun phrases tend to distort the structure of two-dimensional map

RQ1
: what is the output and growth trend of publications in the selected streams? RQ2: which are the most influential countries and journals that are impacting the research streams? RQ3: what is the relationship between internationalisation and eco-innovation and how it is being investigated?

Stage 1: Search Criteria
The first condition for the study was to rely on scientific papers that are investigating eco-innovation and internationalisation as the main concepts. This condition for the keywords was used for several reasons. Firstly, it aimed to ensure that the scientific literature is within the scope of this paper. Secondly, it aimed to ensure that this study did not divert away from the main research questions. Hence, numerous synonyms were used in conjunction with the main keywords and the initial search string was composed of three parts: the first focused on the ecological part using eco OR ecologic OR environment OR sustainable OR green, the second focused on innovations, using innovation and the last focused on internationalisation part, using internationalisation OR export. No quotation marks were included, however an asterisk was included to extract the synonyms. Notably, the filtering of general noun phrases, such as result, study, paper, etc. was crucial (Van Raan 2014), because these general meaning noun phrases tend to distort the structure of two-dimensional map due to their irrelevance compared to the research topic. This search results all had the selected terms identified in the title, the abstract and/or in the keywords of the publications with the indexes SCI-EXPANDED, SSCI, A&HCI, CPCI-S, CPCI-SSH and ESCI.

Stage 2: Database Selection
This study included an information search using Web of Science (or WoS), which is one of the main scientific databases and is the most relevant scientific citation database. It is also a multidisciplinary database, indexing the most cited journals in the respective fields (Pedro et al. 2018), such as SCI-EXPANDED, SSCI, A&HCI, CPCI-S, CPCI-SSH, BKCI-S, BKCI-SSH, ESCI, CCR-EXPANDED and IC (Dabić et al. 2019). Every publication in Web of Science includes many details such as the publication year, authors, addresses, title, abstract, journal, references, etc. (van Nunen et al. 2018).

Stage 3: Data Collection
The search was performed in April 2020. Only empirical research papers were included, as they featured the results of investigations on internationalisation and eco-innovation; therefore, the document type was selected as Article and included the period from 1991 to 2020. The preliminary results of the search in WoS were a total of 1841 articles. In order to analyse the selected keywords, the language filter was applied, which resulted in a total of 1677 papers found that were published in English from 1991 to 2020. Once the data search was finalised, we exported the results with all available information in the ".txt" format, which was used for the analysis.

Stage 4: Data Analysis
After data collection, the selected articles were assessed by considering the chosen streams prior to the data synthesis. This stage let us confirm the relevance of the study. The main ideas in the discovered texts were analysed and their relevance to the eco-innovation and internationalisation was studied.
For quantitative data analysis, the construction and visualisation of bibliometric networks (van Eck and Waltman 2017) was used by applying the free access VOSviewer (www.vosviewer.com) software. VOS viewer software provides a more general view of search results by generating two-dimensional maps based on bibliographic coupling, co-authorship, citation, co-citation, co-occurrence of keywords, authors and countries to visualise relationships between them (van Nunen et al. 2018;Cancino et al. 2017;Gall et al. 2015). The clustering method was used to identify different clusters, where each group is differently coloured (van Eck and Waltman 2017). The clusters were formed by selecting all papers that together are linked by a specified co-citation threshold. The interpretation of visualisation, in general, is as follows: the size of the circles represents the number of occurrences, the distance between two circles reveals similarities and relatedness, different colours mark separate clusters (van Nunen et al. 2018). Cancino et al. (2017) describes the principles and explains that bibliographic coupling links two papers that cite the same third article. Co-citation is a method used to establish subject similarity between two documents. Meanwhile, co-authorship measures the degree of co-authorship between the most productive sources. Citation analysis focuses on the degree of citation similarity between two variables. Co-occurrence of author keywords shows the most common keywords and the network connections visualises the keywords that appear more frequently in the same papers (Van Raan 2014).

Stage 5: Presentation of Results
After data processing and analysis, only the final results and quantitative evaluation of the examined phenomenon are presented in the following sections. The detailed results and visualisations are provided in the results section. The discussion and conclusions sections follow.

The Output and Growth Trend of Publications
To answer RQ1, we measured the output of annual publications. The number of scientific papers is an important measurement for evaluating the development in a specific research discipline or a field. The publications related to eco-innovations and internationalisation increased over the analysed period ( Figure 2). In total 1677 scientific documents were published during the years 1991-2020. There was only one publication in 1991.

The Output and Growth Trend of Publications
To answer RQ1, we measured the output of annual publications. The number of scientific papers is an important measurement for evaluating the development in a specific research discipline or a field. The publications related to eco-innovations and internationalisation increased over the analysed period (Figure 2). In total 1677 scientific documents were published during the years 1991-

The Most Cited Publications
The most cited and influential publications (n = 15) on eco-innovations and internationalisation are presented in Table 1

The Most Cited Publications
The most cited and influential publications (n = 15) on eco-innovations and internationalisation are presented in Table 1

Bibliographic Coupling of Publications
Bibliographic coupling analysis of publications determines the relatedness of publications based on the number of references that they share (Figure 2). The size of the circles represents the number of citations. Meanwhile, the distance represents relatedness and similarities between two publications and the colours represent clusters. Notably, the results meeting a threshold of 50 citations are presented. In total, nine different clusters can be identified (

Bibliographic Coupling of Publications
Bibliographic coupling analysis of publications determines the relatedness of publications based on the number of references that they share (Figure 2). The size of the circles represents the number of citations. Meanwhile, the distance represents relatedness and similarities between two publications and the colours represent clusters. Notably, the results meeting a threshold of 50 citations are presented. In total, nine different clusters can be identified (Figure 3

The Most Cited Journals
Aiming to answer RQ2, we analysed the most cited and influential journals. The most cited and influential journals (n = 15) on eco-innovations and internationalisation are presented in Table 2. The most cited journal is Research Policy with 16 documents and is cited in a total of 2210 citations with an average citations per document of n = 138.13. Second, the most-cited journal is Proceedings of the National Academy of Sciences of the United States of America with 6 documents and in a total of 1476 citations, with average citations per document of n = 246. Third, the most-cited journal is Journal of Operations Management with 2 documents and in a total of 1476 citations, with average citations per document n = 500.

Co-Citation Analysis of Journals
Co-citation analysis of journals determines the relatedness of the journals based on the number of times they are cited together (Figure 4). The size of the circles represents the number of citations, the distance represents relatedness and similarities between two journals while the colours represent clusters. Notably, only the results meeting a threshold of 50 citations are presented. In total, four different clusters can be identified: the cluster in yellow (the most co-cited in the cluster: American Economic Review (n = 431) top left); the cluster in red (the most co-cited in the cluster: Research Policy (n = 1509) bottom left/ middle); cluster in blue (the most co-cited in the cluster: Strategic Management Journal (n = 1543) top right); and cluster in green (the most co-cited in the cluster: Harvard Business Review (n = 459) bottom right). The most co-cited journals are: Strategic Management Journal (n = 1543), Journal of International Business Studies (n = 1519) and Research Policy (n = 1509).

Co-Citation Analysis of Authors
Co-citation analysis of authors determines the relatedness of authors based on the number of times they are cited together ( Figure 5). The size of the circles represents the number of citations. Meanwhile, the distance represents relatedness, similarities and cooperation between the authors and the colours represent clusters. Only the results meeting a threshold of 20 citations are shown. In total, five different clusters can be identified: cluster in purple (Q. Zhu

Co-Authorship Analysis of Countries
To answer RQ2: we analysed the most cited and influential countries. Co-authorship analysis of authors determines the relatedness of countries based on the number of co-authored documents and measures the degree of co-authors between the most productive sources (Figure 6). The size of the circles represents the number of citations. Meanwhile, the distance represents relatedness, similarities and cooperation between countries while the colours represent clusters. In total, six different clusters can be identified: the cluster in yellow (Germany (n = 1061 citations, documents n = 83) left); cluster in green (the United Kingdom (n = 4631 citations, documents n = 191) top left/ middle); cluster in purple (France (n = 976 citations, documents n = 47) top middle); cluster in orange (Taiwan (n = 847 citations, documents n = 39) top right); cluster in red (USA (n = 11,518 citations, documents n = 320) right); cluster in light blue (Spain (n = 1524 citations, documents n = 97) bottom middle); and the cluster in dark blue (Netherlands (n = 2114 citations, documents n = 61) middle). Only the results meeting a threshold of 10 publications on the topic are shown. The USA is predominating with a total of 320 publications (n = 11,518 citations), the United Kingdom is the second largest country (n = 191; citations n = 4631) and the People's Republic of China is the third largest country with total of 172 publications (n = 3468 citations).

Co-Authorship Analysis of Countries
To answer RQ2: we analysed the most cited and influential countries. Co-authorship analysis of authors determines the relatedness of countries based on the number of co-authored documents and measures the degree of co-authors between the most productive sources ( Figure 6). The size of the circles represents the number of citations. Meanwhile, the distance represents relatedness, similarities and cooperation between countries while the colours represent clusters. In total, six different clusters can be identified: the cluster in yellow (Germany (n = 1061 citations, documents n = 83) left); cluster in green (the United Kingdom (n = 4631 citations, documents n = 191) top left/ middle); cluster in purple (France (n = 976 citations, documents n = 47) top middle); cluster in orange (Taiwan (n = 847 citations, documents n = 39) top right); cluster in red (USA (n = 11,518 citations, documents n = 320) right); cluster in light blue (Spain (n = 1524 citations, documents n = 97) bottom middle); and the cluster in dark blue (Netherlands (n = 2114 citations, documents n = 61) middle). Only the results meeting a threshold of 10 publications on the topic are shown. The USA is predominating with a total of 320 publications (n = 11,518 citations), the United Kingdom is the second largest country (n = 191; citations n = 4631) and the People's Republic of China is the third largest country with total of 172 publications (n = 3468 citations).

Keywords
To answer RQ3, we analysed terms that are being used in scientific documents. Co-occurrence of author's keywords analysis determines the relatedness of keywords based on the number of documents in which authors used specific keywords. Figure 7 reveals common keywords used by authors below the abstract to characterise their papers. The size of the circles represents the number of keywords being used, the distance represents relatedness and similarities between keywords and the colours represent clusters. Notably, only the results meeting a threshold of 15 times are presented. The general noun phrases such as result, study, paper, etc. were extracted from the keyword analysis. In total, seven different clusters can be identified: The cluster in orange ("Globalisation" (n = 82) left middle); cluster in dark blue ("Innovation" (n = 162) top left/middle); cluster in light blue ("Internationalisation" (n = 72) top middle); cluster in pink ("Dynamic capabilities" (n = 18) top right); cluster in yellow ("Exports" (n = 27) and "Eco-innovation" (n = 21) bottom right); cluster in green ("Sustainable development" (n = 47) bottom middle), and the cluster in red ("Competitiveness" (n = 33) middle right). The most used keywords by authors below the abstracts to characterise the papers on eco-innovations and internationalisation are "Innovation" (n = 162), "Globalisation" (n = 82) and "Internationalisation" (n = 72).

Keywords
To answer RQ3, we analysed terms that are being used in scientific documents. Co-occurrence of author's keywords analysis determines the relatedness of keywords based on the number of documents in which authors used specific keywords. Figure 7 reveals common keywords used by authors below the abstract to characterise their papers. The size of the circles represents the number of keywords being used, the distance represents relatedness and similarities between keywords and the colours represent clusters. Notably, only the results meeting a threshold of 15 times are presented. The general noun phrases such as result, study, paper, etc. were extracted from the keyword analysis. In total, seven different clusters can be identified: The cluster in orange ("Globalisation" (n = 82) left middle); cluster in dark blue ("Innovation" (n = 162) top left/middle); cluster in light blue ("Internationalisation" (n = 72) top middle); cluster in pink ("Dynamic capabilities" (n = 18) top right); cluster in yellow ("Exports" (n = 27) and "Eco-innovation" (n = 21) bottom right); cluster in green ("Sustainable development" (n = 47) bottom middle), and the cluster in red ("Competitiveness" (n = 33) middle right). The most used keywords by authors below the abstracts to characterise the papers on eco-innovations and internationalisation are "Innovation" (n = 162), "Globalisation" (n = 82) and "Internationalisation" (n = 72).

Discussion and Limitations
The analysis of scientific papers on eco-innovations and internationalisation published from 1991 to 2020 is presented. The study includes 1677 publications and covers 4143 authors, 860 journals, 112 countries and 1889 institutions. The academic literature on analysed topics has been increasing during the last ten years. Thus, the publication output is characterised by exponential growth.

Discussion and Limitations
The analysis of scientific papers on eco-innovations and internationalisation published from 1991 to 2020 is presented. The study includes 1677 publications and covers 4143 authors, 860 journals, 112 countries and 1889 institutions. The academic literature on analysed topics has been increasing during the last ten years. Thus, the publication output is characterised by exponential growth. • The bibliometric analysis provided information on the most influential and productive scholars in the research field: • the most cited publication is by authors E. F. Lambin and P. Meyfroidt with an average of 121.89 citations per year; • the most-cited journal is Research Policy with a total of 2210 citations, the Research Policy journal is also one of the few most co-cited journals with a total of 1509; • the most co-cited author is M. Porter (n = 306); • the country with the largest publication output is the USA (n = 11,518 citations, documents n = 320). Other countries are linked (directly or indirectly) to one of the main countries that are publishing the most scientific documents, thus the data showed that cooperation between authors and countries is mediocre due to the circles' distance from each other; the circles are widely spread, although they are linked together (directly or indirectly).
The power-law distribution lets us observe that: • the largest proportion of authors (95.70%) are only credited in one publication; • a small group of authors (0.73% of all authors) published at least three papers; • among the journals publishing the topic, only 6.05% of journals published more than 5 documents (from a total of 859); • among all countries (total n = 112) publishing on a topic, 36.61% countries published over 10 documents; • a total of 390 publications (23.75% of all publications) was not (yet) cited; • a total of 18 publications (1.10% of all publications) was cited over 200 times.
The distribution corresponds with the study published by van Nunen et al. (2018), which observed that a large proportion of authors, journals and countries do not contribute nearly as much as a much smaller number does and the majority of academic literature is produced by a small group of authors.
Based on author keyword co-occurrence, it is possible to distinguish between four main areas of research: (1) innovations; (2) internationalisation; (3) globalisation; (4) sustainability and sustainable development. Despite its own research stream, all of the main research areas are close to each other in the network analysis and are linked directly together.
The obtained results let us develop the operational model of analysis (Figure 8). The findings of bibliometric analysis and literature review suggest that the rapid growth of globalisation, technology development and digitalisation and sustainable development trends have been impacting the internationalisation process. Moreover, eco-innovation mediates the relationship between internationalisation and financial performance of the firms.
Though bibliometric analysis reduces the bias that is often associated with the expert surveys and traditional reviews, it nevertheless has some limitations. In spite of the benefits for overcoming biases, this method cannot replace rigorous content analysis and overcome its shortcomings, which are that it is a method of quantitative analysis by nature. The number of scientific publications was used as the data in this study. However, it is hardly possible to extensively discuss all the theoretical insights that were presented in the articles. This study is limited to the quantitative method, leaving behind the quality and deeper theoretical knowledge, cornerstones and conclusions presented by the authors in the field of the interrelationship between eco-innovation and internationalisation. Another possible drawback of this study is that citation analysis may be misleading due to authors citing some publications in a negative context or self-citations. The last limitation of this study is tied to a selected timeline. For instance, if a similar study would be performed on a different date, the result would be slightly different. The fact that the WoS database is constantly updated with newer scientific documents affects these changes. Furthermore, some important publications may be cited after many years and gain "delayed recognition" in the scientific literature. These limitations can be considered in future studies.
observed that a large proportion of authors, journals and countries do not contribute nearly as much as a much smaller number does and the majority of academic literature is produced by a small group of authors.
Based on author keyword co-occurrence, it is possible to distinguish between four main areas of research: (1) innovations; (2) internationalisation; (3) globalisation; (4) sustainability and sustainable development. Despite its own research stream, all of the main research areas are close to each other in the network analysis and are linked directly together.
The obtained results let us develop the operational model of analysis (Figure 8). The findings of bibliometric analysis and literature review suggest that the rapid growth of globalisation, technology development and digitalisation and sustainable development trends have been impacting the internationalisation process. Moreover, eco-innovation mediates the relationship between internationalisation and financial performance of the firms. Though bibliometric analysis reduces the bias that is often associated with the expert surveys and traditional reviews, it nevertheless has some limitations. In spite of the benefits for overcoming biases, this method cannot replace rigorous content analysis and overcome its shortcomings, which are that it is a method of quantitative analysis by nature. The number of scientific publications was used as the data in this study. However, it is hardly possible to extensively discuss all the theoretical insights that were presented in the articles. This study is limited to the quantitative method, leaving behind the quality and deeper theoretical knowledge, cornerstones and conclusions presented by the authors in the field of the interrelationship between eco-innovation and internationalisation. Another possible drawback of this study is that citation analysis may be misleading due to authors citing some publications in a negative context or self-citations. The last limitation of this study is tied to a selected timeline. For instance, if a similar study would be performed on a different date, the result would be slightly different. The fact that the WoS database is constantly updated with newer scientific documents affects these changes. Furthermore, some important publications may be cited after many years and gain "delayed recognition" in the scientific literature. These limitations can be considered in future studies.

Conclusions
While the expectations of various stakeholders encourage firms to be involved in risky activities, such as the adoption of eco-innovation and internationalisation, we set forth to investigate the interrelationship between eco-innovation and internationalisation by applying bibliometric analysis. The study addressed the research gap emphasising that eco-innovation and internationalisation are barely related factors (Chiarvesio et al. 2015). In total, 1677 publications found in the WoS database

Conclusions
While the expectations of various stakeholders encourage firms to be involved in risky activities, such as the adoption of eco-innovation and internationalisation, we set forth to investigate the interrelationship between eco-innovation and internationalisation by applying bibliometric analysis. The study addressed the research gap emphasising that eco-innovation and internationalisation are barely related factors (Chiarvesio et al. 2015). In total, 1677 publications found in the WoS database that were published between 1991 and 2020 related to eco-innovations and took internationalisation into consideration.
Considering the dynamics in economical, ecological and social environments, we argue that both eco-innovations and internationalisation are closely related and the research trends on interrelationships between eco-innovations and internationalisation study fields are constantly increasing. This is confirmed by the fact of exponential growth of scientific publications on selected topics each year. However, the most influential countries affecting research on these topics are developed countries, such as the USA and the United Kingdom. It appears that the most significant actions on political and company levels are taken toward sustainable development in these countries. However, future investigations have to consider developing countries as well.
We outline a future research agenda to create a more holistic theoretical approach on eco-innovations and internationalisation. By using the fractional counting method for keywords, different trends have been identified involving globalisation and supply chain management. Other interesting interactions between most frequent terms and related to innovation occur for green innovation, technological innovation and product innovation. Thus, future studies should investigate the interrelationships of the selected terms on the dimensions of sustainable development and internationalisation. In addition, other databases such as Scopus have to be taken into account. Also based on the presented limitations of bibliometric analysis, deeper content analysis is recommended for further research.

Conflicts of Interest:
The authors declare no conflict of interest.