Não informado. (1961). Agricultural Economic Report. U.S. Department of Agriculture, Economics, Statistics and Cooperative Service.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Agricultural Economic Report. Washington: U.S. Department of Agriculture, Economics, Statistics and Cooperative Service, 1961.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Agricultural Economic Report. U.S. Department of Agriculture, Economics, Statistics and Cooperative Service, 1961.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.