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.
Ziegler LE, Craigs CL, West RM, Carder P, Hurlow A, Millares-Martin P, Hall G, Bennett MI.Ziegler LE, et al.BMJ Open. 2018 Jan 31;8(1):e018284. doi: 10.1136/bmjopen-2017-018284.BMJ Open. 2018.PMID: 29386222Free PMC article.