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.
Losi A, Gärtner W.Losi A, et al.Photochem Photobiol. 2011 May-Jun;87(3):491-510. doi: 10.1111/j.1751-1097.2011.00913.x. Epub 2011 Mar 23.Photochem Photobiol. 2011.PMID: 21352235Review.