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.
Figure reproduced from (Levenesque et al. 2013) under the terms of the Creative Commons Attribution 2.0 Generic License (CC BY 2.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
