Full text
PDFPage 666
. 1975 Aug;50(8):666. doi: 10.1136/adc.50.8.666-a
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.