Full text
PDF
. 1987 Apr 18;294(6578):1017–1018. doi: 10.1136/bmj.294.6578.1017-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.
