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.
Openshaw S, Charlton M.Openshaw S, et al. Among authors: charlton m.Br Med J. 1980 Sep 13;281(6242):742-3. doi: 10.1136/bmj.281.6242.742-b.Br Med J. 1980.PMID: 7427420Free PMC article.No abstract available.