Παραπομπή APA

Roberts, I. P. (1911). Fertility of the Land (12.). Macmillan Company.

Παραπομπή Chicago Style

Roberts, Issac Phillip. Fertility of the Land. 12. New York: Macmillan Company, 1911.

Παραπομπή MLA

Roberts, Issac Phillip. Fertility of the Land. 12. Macmillan Company, 1911.