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.
(A) The co-citation network visualization map of references based on VOSviewer; (B) The density visualization map of references based on VOSviewer; (C) Top 25 references with the strongest citation bursts based on CiteSpace, The red horizontal stripes represent the years with the most frequent publications. The green horizontal stripes represent the years with the most infrequent publications.
