Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Map of the co-occurrence network of the 75 selected keywords. The prominence of the circles and texts in each cluster represents the strength of their co-occurrence, while the distance of the elements and lines shows the relation and linkage among the different keywords, respectively. (A) shows the grouping of keywords into four clusters, while (B) shows the publication period, ranging from 2012 (blue) to 2022 (red).
