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.
Wood AW, Chang RL, Levin W, Lehr RE, Schaefer-Ridder M, Karle JM, Jerina DM, Conney AH.Wood AW, et al.Proc Natl Acad Sci U S A. 1977 Jul;74(7):2746-50. doi: 10.1073/pnas.74.7.2746.Proc Natl Acad Sci U S A. 1977.PMID: 331315Free PMC article.