Citazione APA

Keffer, C. A. (1907). Nature studies on the farm: Soils and plants. American Book Co..

Stile di citazione Chicago

Keffer, Charles A. Nature Studies on the Farm: Soils and Plants. New York: American Book Co., 1907.

Citazione MLA

Keffer, Charles A. Nature Studies on the Farm: Soils and Plants. American Book Co., 1907.