Figure 9.
Top 5 (a); 10 (b); 15 (c) subject-independent channels according to a 10–20 system.
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.