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.
Roper WL, Thacker SB.Roper WL, et al.Ann N Y Acad Sci. 1993 Dec 31;703:33-9; discussion 39-40. doi: 10.1111/j.1749-6632.1993.tb26332.x.Ann N Y Acad Sci. 1993.PMID: 8192314No abstract available.
Gordon RL, Baker EL, Roper WL, Omenn GS.Gordon RL, et al. Among authors: roper wl.Annu Rev Public Health. 1996;17:489-509. doi: 10.1146/annurev.pu.17.050196.002421.Annu Rev Public Health. 1996.PMID: 8724237Review.