APA-referens (7:e uppl.)

Hopkins, C. G. (1910). Soil fertility and permanent agriculture. Ginn.

Chicago-referens (17:e uppl.)

Hopkins, Cyril G. Soil Fertility and Permanent Agriculture. Boston, New York: Ginn, 1910.

MLA-referens (8:e uppl.)

Hopkins, Cyril G. Soil Fertility and Permanent Agriculture. Ginn, 1910.