Não informado. (1941). Crop Production. Department of Agriculture, Statistical Reporting Service.
Chicago-referens (17:e uppl.)Não informado. Crop Production. Washington: Department of Agriculture, Statistical Reporting Service, 1941.
MLA-referens (8:e uppl.)Não informado. Crop Production. Department of Agriculture, Statistical Reporting Service, 1941.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.