Cita APA (7a ed.)

Hopkins, D. P. (1948). Chemicals, humus, and the soil: A simple presentation of contemporary knowledge and opinions about fertilizers, manures and soil fertility. Chemical.

Cita Chicago Style (17a ed.)

Hopkins, Donald P. Chemicals, Humus, and the Soil: A Simple Presentation of Contemporary Knowledge and Opinions About Fertilizers, Manures and Soil Fertility. New York: Chemical, 1948.

Cita MLA (8a ed.)

Hopkins, Donald P. Chemicals, Humus, and the Soil: A Simple Presentation of Contemporary Knowledge and Opinions About Fertilizers, Manures and Soil Fertility. Chemical, 1948.