Full Text
The Full Text of this article is available as a PDF (244.0 KB).
letter . 1998 Feb 14;316(7130):552–553. doi: 10.1136/bmj.316.7130.552a
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.