Figure 2.
A global network of the most prolific countries (more than 50 papers). Note: America = Red; Europe = Green; Blue = Australia; Asia = Yellow, Africa & Middle East = Yellow.
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.