Não informado. (2001). Bibliography of Agriculture. U.S. Department of Agriculture.
Chicago-referens (17:e uppl.)Não informado. Bibliography of Agriculture. Washington: U.S. Department of Agriculture, 2001.
MLA-referens (8:e uppl.)Não informado. Bibliography of Agriculture. U.S. Department of Agriculture, 2001.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.