Table 2.

Clusters by bibliometric coupling of documents

Cluster*	Authors (Citations)
Cluster 1 – red	Anderson (6) [43]; Barr (36) [2]; Buse and Walt (161) [16]; Gupta et al. (97) [44]; Hein and Kohlmorgen (17) [45]; Johnston and Finegood (27) [5]; Lo (128) [46]; Molyneux and Zagaria (128) [47]; Peters and Phillips (37) [48]; Streefland (24) [49]; Vian et al. (22) [50]; Wheeler and Berkley (36) [51].
Cluster 2 – green	Ejaz et al. (20) [52]; Holden (20) [25]; Jacobs et al. (15) [53]; La Forgia and Harding (20) [54]; McIntosh et al. (8) [30]; Palmer and Mills (20) [55]; Palmer (10) [26]; Sekhri et al. (23) [56]; Whyle and Olivier (9) [23].
Cluster 3 – blue	Abuduxike and Aljunid (9) [57]; Barker et al. (7) [58]; Bottazzi et al. (15) [59]; Bottazzi and Brown (10) [60]; Hendriks et al. (6) [61]; Hotez and Ferris (119) [62]; Mahoney (18) [63].
Cluster 4 – yellow	Lambert et al. (18) [64]; Lei et al. (13) [65]; Naqvi et al. (18) [66]; Newell et al. (14) [67]; Saw et al. (10) [68]; Tin et al. (14) [69].
Cluster 5 – violet	Kruk et al. (14) [70]; Mwisongo and Nabyonga-Orem (9) [71]; Rao et al. (12) [72]; Saxenian et al. (23) [71].
Cluster 6 - light blue	Ali et al. (22) [73]; Basit et al. (7) [74]; Nishtar (10) [17]; Nishtar et al. (17) [75].
Cluster 7 – orange	Meredith et al. (23) [76]; Zhang et al. (39) [77]; Zhou et al. (12) [78].
Cluster 8 – brown	Alemnji et al. (22) [79]; Alemnji et al. (25) [80].

* The colour of each cluster is the same as that in the relative “bubble” shown in Fig. 4