Fig. 3

Authors co-citation network Cluster 1 (9) [red]; Cluster 2 (5) [green], Cluster 3 (3) [blue]). Note: The minimum author’s citation threshold was set at 20 and of the 4687 authors, only 17 met the criteria. The bubble size indicates the most cited author, while the colour refers to the clustering and line thickness the strength of the corresponding link