# A Review of Digital Era Governance Research in the First Two Decades: A Bibliometric Study
## 4 Results
### Network Analysis  
Figure 7 shows the co-authorship network, which reveals authors' collaboration within the largest connected component in DEG research, where the nodes represent authors and the links the co-authorship relations between authors. Note that the node size is in proportion to the number of an author's publications (node degree), the link width is in proportion to the number of joint publications (edge weight), while the node colour indicates the cluster to which an individual author belongs [64]. The analysis complements the existing authors' collaboration based on the Web of Science [33] and shows that collaboration occurs mainly within five narrow and isolated groups of researchers. [PERSON] and [PERSON] are researchers at the same university (Delft University of Technology, Netherlands), dealing mainly with topics related to _open data_. Similarly, [PERSON]. (University of the Aegean, Greece) and three other related authors besides _open data_ address topics related to _interoperability_. Further, while [PERSON]. (Brunel University, UK) and eight other related authors address _e-government implementation_, [PERSON]. (Swansea University, UK) and two more authors go a step further by addressing selected issues about _e-government adoption_. Finally, [PERSON] (State University of New York Albany, USA) and five other related authors especially address research topics related to _collaborative e-government_ and _smart government_. Some of these authors are considered to be the most relevant in DEG research (see Figure 6). Figure 8 presents the keyword co-occurrence network for DEG research, where the nodes represent keywords and the links the co-occurrence relations between keywords. It is conducted on the authors' 50 most frequent keywords by consolidating keywords that describe the same phenomenon (e.g., digital government or e-government). Note that the node size is in proportion to the number of keyword occurrences, showing research intensity (node degree), the link width is in proportion to the co-occurrences between keywords (edge weight), while the node colour indicates the cluster to which a particular keyword belongs [64]. The authors' keyword co-occurrence network shows the research hotspots in DEG research and supplements the findings from the Web of Science database [33]. Eight clusters are thus identified: (1) _open government_; (2) _government  
Figure 6: Most relevant authors by the number of documents and citations in DEG research (2001–2020). and ICT; (3) e-governance; (4) e-government; (5) adoption in developing countries; (6) trust and security; (7) evaluation and implementation; and (8) interoperability. A detailed synopsis of the research hotspots, including the top keywords related to DEG research, is presented in Table A1 in the Appendix A. When considering the time dimension, certain terms appeared to be more important at the start of the observed period (e.g., _communication technologies_, _government_, _information systems_ and _internet_), whereby e-government_ and other related terms (e.g., _e-governance_, _e-democracy_) appear to be more important somewhere in the middle of the observed period. As expected, _social media_, _open government_, _big data_, _open data_ and _smart city_ are terms that became important in the last quarter of that period [17]. Figure 8: Authors’ keyword co-occurrence in DEG research. Figure 7: Co-authorship network showing authors’ collaboration on DEG research. The critical path presented in Figure 9 indicates the milestone documents, helping to reveal the evolution of DEG research. It extends earlier evidence from the Web of Science database [17]. The critical path was conducted by considering the following steps. The initial set of 9175 documents obtained from the Scopus database was narrowed down to documents also indexed in the Web of Science database, resulting in 2993 documents. Moreover, based on Bradford's law, the set of documents was further narrowed down to nine key sources, resulting in 641 documents.