Three Decades of Research on Smart Cities: Mapping Knowledge Structure and Trends
Round 1
Reviewer 1 Report
The article presents a very interesting topic in an efficient way. However, with the view to improving further this article, I would like to highlight the following points. First, the title also refers to “mapping knowledge structure”; however, this is not justified by the analysis done in the article. To my understanding, the article includes a sufficient analysis of trends rather than the mapping knowledge structure. I would therefore suggest to give more emphasis to the part of the structure by briefly explaining the results of the bibliometric analysis taking also into consideration the current main conditions of the cities for the periods under consideration.
Hence, the question that arises is, beyond the results of bibliometric analysis, how sub-periods are distinguished in the article? For example, how does this relate either to government policies that may boost the smartness of cities or to other milestones of the period? Either in Europe or internationally.
Furthermore, lines 170 - 171 refer to an importing data issue (…we used a broad-based search string that includes two keywords: smart city and smart cities). More information could be given on this point given that the way the search criteria are set out has a decisive influence on the results of the research. I would also expect to see more information on the parameters set out for co-occurrence analysis, citation, co-citation, and bibliographic coupling to occur.
Overall, it is a very interesting article that introduces a fruitful dialogue on a hot topic. I hope these comments are helpful and will improve the manuscript and encourage the authors to move forward with their research.
Author Response
Please see attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear Authors,
your research sounds promising, but some changes are needed to move it to next levels. Please find below my comments:
Abstract:
since there's a scant of papers until 2010, why did you split the dataset without considering this information and - at least until the end of the abstract - without no further reasons?
Introduction
a smart city can't have the ''ability to assist cities''; I would rephrase this sentence.
Line 55: 'in in' please amend
'technologically oriented products' doesn't seem the right wording for solutions to smart cities.
You moved quite abruptly from definitions to data on the market of smart solutions for city. Please try to link these 2 elements better.
At the end of page 2 you referred to cities that 'will continue to emerge', thus I think it would be suitable to refer to the born smart cities instead of just focusing on the transformed ones.
P. 3: you state that 'definitions for the smart city has led to a number of terminologies such as the Intelligent City and Digital city': the 2 nouns/definitions you recalled came before smart city, while you stated the opposite.
I agree with recalling sources 39 & 40, but there are key contributions in the smart cities debate (e.g., Giffinger et al., 2007) that you skipped.
'To the best of our knowledge, there are only a few bibliometric studies on smart cities research [41-43].': there are more, also on the comparison between smart and sustainable cities and other similar comparisons. Please amend.
'Smart Cities on the other end, seem to tap into the premise of the thriving fourth industrial revolution': actually - as you stated at the beginning - Smart Cities emerged hugely before Industry 4.0. I am recalling both theoretical advances and empirical ones.
Section 2
Did you consider all types of contribution? What about proceedings for instance?
Did you filter the contributions due to the language they were written in? Please describe, including any other type of criterion (e.g. the type of publication).
Line 185: there's a mistake in the link
What is new in your review compared to the ones sourced 43-45?
'Also, 2015 was selected as a milestone considering that different reports that may have influenced smart city research were published in that year': you know the publication process of papers can take long. And the publishing year may be different compared to the year in which the article got accepted and also written. I found this kind of splitting very biased and scarcely justified.
Results:
you referred to articles and publications: does this mean you discarded chapters? Please describe in the section about method
Lines 220-234 are exactly the same than lines 241-255.
Is the co-occurrence based on the entire dataset or just on the 2nd half (from 2015 on)? This would clarify the dominance of definitory studies. (The results in 3.2.2 gives an hint on the overview in the first section only later)
'colored by in figure 2 below' looks incomplete. Additionally, the figure is above.
The analysis of the 3 thematic clusters disregards one key topic: sustainable cities.
'During this period, it is observable that the term ‘renewable energy’ has disappeared in the ‘blue’ cluster': did it lose attention or was disregarded at all?
Line 440: I would not define ridesharing a technology
'that are mainly focused Internet of Things (IoT) and' -> 'that are mainly focused ON Internet of Things (IoT) and'
Section 3.4 should offer examples of contributions/publications as you did in the other sub-sections
Figure 10 recalls most of the very influential authors, but I wonder how Giffinger is out of this analysis. I may recall at least 2 works that are widely cited (and that I cited various times when writing on smart cities), namely
Giffinger, R., & Gudrun, H. (2010). Smart cities ranking: an effective instrument for the positioning of the cities?. ACE: architecture, city and environment, 4(12), 7-26.
and
Giffinger, R., Fertner, C., Kramar, H., & Meijers, E. (2007). City-ranking of European medium-sized cities. Cent. Reg. Sci. Vienna UT, 1-12.
I'm not saying that you should cite him forcely, but can you provide a reason for him not being in this analysis in the diagram on p. 16?
Discussion: I am left with a 'so-what' feeling, since there are no implications at all. Discussions are fine, but you should identify research priorities, any future research directions (you have just one in lines 627-628). Additionally, I would highlight the limitations of this research, as soon as the method section would be updated.
Kind regards
Author Response
Please find the attached document which includes point-by-point responses to the reviewer's comment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The manuscipt has been considerably improved.
Author Response
Please find the attached.
Reviewer 2 Report
Dear Authors,
I appreciate most of your changes and they lead to a now complete and significant contribution. I have two minor concerns:
'Literature search was conducted on April 24, 2021, for an unlimited time period,': please check how you wrote this sentence as it seems the research you made is endless
'All types of publications were included in the analysis. The search returned 7,228 documents, and after excluding irrelevant studies': I would replace irrelevant with 'out of scope' or any other way you may replace irrelevant.
Regards
Author Response
Please find the attached.
Author Response File: Author Response.pdf
