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.
The diameter of each circle is directly proportional to the annual number of publications. USA: United States of America; BRA: Brazil; JPN: Japan; IND: India; MEX: Mexico; CHN: China; SAF: South Africa; FRA: France; SPN: Spain; CAN: Canada; GER: Germany; NTL: The Netherlands; GBR: Great Britain; ITA: Italy; AUS: Australia.
