Citazione APA

Iowa. State Planning Board. Soil Conservation Committee. (1938). Soil conservation districts for Iowa? Iowa State Planning Board.

Stile di citazione Chicago

Iowa. State Planning Board. Soil Conservation Committee. Soil Conservation Districts for Iowa? [Des Moines]: Iowa State Planning Board, 1938.

Citazione MLA

Iowa. State Planning Board. Soil Conservation Committee. Soil Conservation Districts for Iowa? Iowa State Planning Board, 1938.

Attenzione: Queste citazioni potrebbero non essere precise al 100%.