Cita APA (7th ed.)

Waksman, S. A. (1938). Humus: Origin, chemical composition, and importance in nature (2a. ed.). Williams and Wilkins.

Cita Chicago (17th ed.)

Waksman, Selman A. Humus: Origin, Chemical Composition, and Importance in Nature. 2a. ed. Baltimore: Williams and Wilkins, 1938.

Cita MLA (9th ed.)

Waksman, Selman A. Humus: Origin, Chemical Composition, and Importance in Nature. 2a. ed. Williams and Wilkins, 1938.