Full text
PDF
letter . 1979 Dec 15;2(6204):1588–1589. doi: 10.1136/bmj.2.6204.1588-e
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.