## 4 Co-Authorship Analysis
### Country-Based Co-Authorship Analysis  
This subsection presents an analysis of co-authorships among countries engaged in OT security research. A VosViewer search found 72 nations, with only 52 meeting the specified criteria. Table 5 displays the top fifteen countries with a total of 50 with the highest TLS values. The total strength of fractional connections within a single country for each published paper will consistently equal one; therefore, the co-authorship-based TLS for the country is invariably an integer. Thus, a country's overall co-authorship link strength across all published papers equals its article count (Np). Nevertheless, this pattern does not apply to Table 5 since the TLS represents an integer that is smaller than the overall number of publications (Np). This observation suggests that some published works lack international co-authors. It is also plausible that some studies included co-authors exclusively from countries with fewer than three OT security papers and/or five WoS citations and were therefore omitted from our analysis. Table 5 outlines the top fifteen countries with the most significant TLS metrics in OT security, as referenced in WoS publications. The USA, with 204 publications, has a TLS value of 74, while the PRC is next with a TLS of 44 and a total of 209 publications. Singapore holds the third spot with 44 publications and a TLS of 33, which is considerably lower compared to the leaders occupying the first and second positions. Other ranking participants are from 19 (Sweden) to 54 (Germany, India) by the number of publications and from 11 (France, Sweden) to 26 (England) by TLS.  
Figure 16: A visual representation of the co-authorship network among organizations within the domain of OT security.  
Figure 17 illustrates the co-authorship network diagram across various countries. This network employs distinct colors to denote various groups within the research network. The varying thickness of the connecting lines indicates the differing strengths of the links between countries. As before, the PRC and the USA stand out as dominant figures in the network. Other noticeable and potentially growing nodes would be Singapore, India, and France. We can also see that bigger nodes typically have more research links to other countries, while smaller players (e.g., Belgium, Iran, or Croatia) have just one or two connections. Still, we would like to stress the attention that the collaboration potential in the sphere of OT security, especially for smaller players, remains not used in full measure.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Rank** & **Country** & **Np** & **Links** & **TLS** \\ \hline
1 & USA & 204 & 26 & 74 \\
2 & Peoples R China & 209 & 25 & 44 \\
3 & Singapore & 44 & 14 & 33 \\
4 & England & 37 & 21 & 26 \\
5 & Saudi Arabia & 32 & 22 & 23 \\
6 & Canada & 38 & 14 & 22 \\
7 & Australia & 37 & 15 & 19 \\
8 & United Arab Emirates & 22 & 15 & 19 \\
9 & India & 54 & 15 & 15 \\
10 & Germany & 54 & 10 & 14 \\
11 & Spain & 28 & 9 & 14 \\
12 & Italy & 30 & 11 & 13 \\
13 & South Korea & 51 & 10 & 12 \\
14 & France & 37 & 9 & 11 \\
15 & Sweden & 19 & 11 & 11 \\ \hline \end{tabular}
\end{table}
Table 5: The top fifteen countries with the highest TLS values.  
Figure 17: A visual representation of the co-authorship network among countries within the domain of OT security.