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.
Chan CH, Ho AK, Chan RC, Cheung H, Cheng AF.Chan CH, et al. Among authors: cheng af.Postgrad Med J. 1992 Nov;68(805):896-9. doi: 10.1136/pgmj.68.805.896.Postgrad Med J. 1992.PMID: 1494510Free PMC article.