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.
Friedman M, Greenwood FC.Friedman M, et al. Among authors: greenwood fc.Proc R Soc Med. 1967 Sep;60(9):910-1.Proc R Soc Med. 1967.PMID: 4293430Free PMC article.No abstract available.