Não informado. Scientific information activities of federal agencies. U.S. National Science Foundation.
Chicago-referens (17:e uppl.)Não informado. Scientific Information Activities of Federal Agencies. Washington: U.S. National Science Foundation.
MLA-referens (8:e uppl.)Não informado. Scientific Information Activities of Federal Agencies. U.S. National Science Foundation.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.