APA (7th ed.) Zitazioa

Curtis, B. (1981). William Graham Sumner. Twayne.

Chicago Style (17th ed.) Zitazioa

Curtis, Bruce. William Graham Sumner. Boston: Twayne, 1981.

MLA (9th ed.) Zitazioa

Curtis, Bruce. William Graham Sumner. Twayne, 1981.