Não informado. (1939). Feed situation. U.S. Department of Agriculture, Bureau of Agricultural Economics.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Feed Situation. Washington: U.S. Department of Agriculture, Bureau of Agricultural Economics, 1939.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Feed Situation. U.S. Department of Agriculture, Bureau of Agricultural Economics, 1939.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.