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.
Hellmeyer L, Meyer-Wittkopf M, Ziegler A, Ballast A, Sierra F, Schmidt S.Hellmeyer L, et al.Ultraschall Med. 2001 Aug;22(4):167-71. doi: 10.1055/s-2001-16812.Ultraschall Med. 2001.PMID: 11524694German.