An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Trenholme GM, Williams RL, Patterson EC, Frischer H, Carson PE, Rieckmann KH.Trenholme GM, et al. Among authors: patterson ec.Bull World Health Organ. 1974;51(4):431-4.Bull World Health Organ. 1974.PMID: 4549495Free PMC article.