Iowa. State Planning Board. Soil Conservation Committee. (1938). Soil conservation districts for Iowa? Iowa State Planning Board.
Chicagoスタイル(17版)引用形式Iowa. State Planning Board. Soil Conservation Committee. Soil Conservation Districts for Iowa? [Des Moines]: Iowa State Planning Board, 1938.
MLA(8版)引用形式Iowa. State Planning Board. Soil Conservation Committee. Soil Conservation Districts for Iowa? Iowa State Planning Board, 1938.
警告: この引用は必ずしも正確ではありません.