APA

United States Departament of Agriculture U., . (1940). Yearbook of agriculture 1940 : farmer's in a changing world. Washington: United States Government Printing Office.

Chicago

United States Departament of Agriculture Usda, . 1940. Yearbook of agriculture 1940 : farmer's in a changing world. Washington: United States Government Printing Office.

Harvard

United States Departament of Agriculture U., . (1940). Yearbook of agriculture 1940 : farmer's in a changing world. Washington: United States Government Printing Office.

MLA

United States Departament of Agriculture Usda, . Yearbook of agriculture 1940 : farmer's in a changing world. Washington: United States Government Printing Office. 1940.