APA-referens (7:e uppl.)

Sumner, W. G., & Keller, A. G. (1914). The challenge of facts: And other essays. Yale University Press; [etc., etc.].

Chicago-referens (17:e uppl.)

Sumner, William Graham, och Albert Galloway Keller. The Challenge of Facts: And Other Essays. New Haven: Yale University Press; [etc., etc.], 1914.

MLA-referens (8:e uppl.)

Sumner, William Graham, och Albert Galloway Keller. The Challenge of Facts: And Other Essays. Yale University Press; [etc., etc.], 1914.