Official websites use .gov A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Bethesda, Md. : U.S. Dept. of Health and Human Services, National Institutes of Health, National Library of Medicine ; Springfield, VA : Available from U.S. Dept. of Commerce, National Technical Information Service, [1988]