Fig. 3: Literature trends.

Bibliometric analysis on the cooccurrence of keywords reported in literature (a). The node size indicates the frequency of occurrence of a specific keyword. The curves connecting between the nodes denotes keywords cooccurrence in the same publication. If the distance between the two keywords are shorter, it signifies greater number of their cooccurrence. b The font size of a keyword in the word cloud represents its frequency of occurrence. Keywords with larger font size indicates their greater occurrence.