Full Text
The Full Text of this article is available as a PDF (310.8 KB).
. 1996 Nov;66(3):391–409. doi: 10.1901/jeab.1996.66-391
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.