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.
Kidder GW, Nolan LL.Kidder GW, et al.Proc Natl Acad Sci U S A. 1979 Aug;76(8):3670-2. doi: 10.1073/pnas.76.8.3670.Proc Natl Acad Sci U S A. 1979.PMID: 291031Free PMC article.