Não informado. (1931). Dairy situation. U.S. Department of Agriculture, Economic Research Service.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Dairy Situation. Washington: U.S. Department of Agriculture, Economic Research Service, 1931.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Dairy Situation. U.S. Department of Agriculture, Economic Research Service, 1931.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.