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.
Venkitaraman AR, Cowling RJ.Venkitaraman AR, et al. Among authors: cowling rj.Proc Natl Acad Sci U S A. 1992 Dec 15;89(24):12083-7. doi: 10.1073/pnas.89.24.12083.Proc Natl Acad Sci U S A. 1992.PMID: 1465444Free PMC article.