Não informado. (1968). Foreign agriculture. U.S. Department of Agriculture, Foreign Agricultural Service.
Chicago-referens (17:e uppl.)Não informado. Foreign Agriculture. Washington: U.S. Department of Agriculture, Foreign Agricultural Service, 1968.
MLA-referens (8:e uppl.)Não informado. Foreign Agriculture. U.S. Department of Agriculture, Foreign Agricultural Service, 1968.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.