Não informado. (1979). Foreign agriculture circular. U.S. Department of Agriculture, Foreign Agricultural Service.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Foreign Agriculture Circular. Washington: U.S. Department of Agriculture, Foreign Agricultural Service, 1979.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Foreign Agriculture Circular. U.S. Department of Agriculture, Foreign Agricultural Service, 1979.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.