Fig. 1.
Flow diagram for systematically identifying a sample of websites.
*URLs were excluded by applying eligibility criteria hierarchically (ordered from left to right in the flow diagram).
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.