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.
Fanning AS, Anderson JM.Fanning AS, et al.Ann N Y Acad Sci. 2009 May;1165:113-20. doi: 10.1111/j.1749-6632.2009.04440.x.Ann N Y Acad Sci. 2009.PMID: 19538295Free PMC article.Review.