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.
Sweeney CT, Shopland DR, Hartman AM, Gibson JT, Anderson CM, Gower KB, Burns DM.Sweeney CT, et al. Among authors: gibson jt.J Am Med Womens Assoc (1972). 2000 Fall;55(5):311-5.J Am Med Womens Assoc (1972). 2000.PMID: 11070655
Soulakova J, Davis WW, Hartman A, Gibson J.Soulakova J, et al.Surv Res Methods. 2009 Jan 1;3(3):123-137.Surv Res Methods. 2009.PMID: 21841957Free PMC article.