Não informado. (1979). Foreign agriculture circular. U.S. Department of Agriculture, Foreign Agricultural Service.
Chicago-referens (17:e uppl.)Não informado. Foreign Agriculture Circular. Washington: U.S. Department of Agriculture, Foreign Agricultural Service, 1979.
MLA-referens (8:e uppl.)Não informado. Foreign Agriculture Circular. U.S. Department of Agriculture, Foreign Agricultural Service, 1979.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.