Não informado. (1961). Agricultural Economic Report. U.S. Department of Agriculture, Economics, Statistics and Cooperative Service.
Chicago-referens (17:e uppl.)Não informado. Agricultural Economic Report. Washington: U.S. Department of Agriculture, Economics, Statistics and Cooperative Service, 1961.
MLA-referens (8:e uppl.)Não informado. Agricultural Economic Report. U.S. Department of Agriculture, Economics, Statistics and Cooperative Service, 1961.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.