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 network of cooperation between countries/regions. (B) The network of cooperation between institutions based on VOSviewer. Node size indicates the number of publications; the link size refers to the cooperation Intensity; the earlier contributions were presented in darker colors.
