Full Text
The Full Text of this article is available as a PDF (82.4 KB).
. 1980;12(3):299. [Article in French] doi: 10.1186/1297-9686-12-3-299
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.