U.S. Soil Conservation Service. (1939). Conservation of the soil; a unit for elementary schools developed by the Fairbrother-Rossell School, in cooperation with the Soil Conservation Service, USDA. s.n.
Citação do estilo Chicago (17ª ed.)U.S. Soil Conservation Service. Conservation of the Soil; a Unit for Elementary Schools Developed by the Fairbrother-Rossell School, in Cooperation with the Soil Conservation Service, USDA. Washington, D. C: s.n, 1939.
Citação MLA (9ª ed.)U.S. Soil Conservation Service. Conservation of the Soil; a Unit for Elementary Schools Developed by the Fairbrother-Rossell School, in Cooperation with the Soil Conservation Service, USDA. s.n, 1939.
Nota: a formatação da citação pode não corresponder 100% ao definido pela respectiva norma.