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.
Dott W, Kämpfer P.Dott W, et al. Among authors: kampfer p.Schriftenr Ver Wasser Boden Lufthyg. 1989;80:119-46.Schriftenr Ver Wasser Boden Lufthyg. 1989.PMID: 2658025Review.German.