Full text
PDFPage 970-1
. 1971 May;21(5):970.1. doi: 10.1128/am.21.5.970.1-970.1.1971
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.