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.
Francis MD, Russell RG, Fleisch H.Francis MD, et al. Among authors: fleisch h.Science. 1969 Sep 19;165(3899):1264-6. doi: 10.1126/science.165.3899.1264.Science. 1969.PMID: 4308521