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.
Viellas EF, da Gama SG, Theme Filha MM, Leal Mdo C.Viellas EF, et al. Among authors: leal mdo c.Rev Bras Epidemiol. 2012 Sep;15(3):443-54. doi: 10.1590/s1415-790x2012000300001.Rev Bras Epidemiol. 2012.PMID: 23090294Free article.Portuguese.