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.
Richards P, McManus IC, Maitlis SA.Richards P, et al.Br Med J (Clin Res Ed). 1988 May 28;296(6635):1520-1. doi: 10.1136/bmj.296.6635.1520.Br Med J (Clin Res Ed). 1988.PMID: 3134096Free PMC article.