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.
Cooney RV, Franke AA, Harwood PJ, Hatch-Pigott V, Custer LJ, Mordan LJ.Cooney RV, et al. Among authors: harwood pj.Proc Natl Acad Sci U S A. 1993 Mar 1;90(5):1771-5. doi: 10.1073/pnas.90.5.1771.Proc Natl Acad Sci U S A. 1993.PMID: 8446589Free PMC article.