Iowa. State Planning Board. Soil Conservation Committee. (1938). Soil conservation districts for Iowa? Iowa State Planning Board.
Chicago Style (17th ed.) CitationIowa. State Planning Board. Soil Conservation Committee. Soil Conservation Districts for Iowa? [Des Moines]: Iowa State Planning Board, 1938.
MLA引文Iowa. State Planning Board. Soil Conservation Committee. Soil Conservation Districts for Iowa? Iowa State Planning Board, 1938.
警告:这些引文格式不一定是100%准确.