Dyfyniad APA

Sumner, W. G., & Keller, A. G. (1914). The challenge of facts, and other essays. Yale University Press.

Dyfyniad Arddull Chicago

Sumner, William Graham, and Albert Galloway Keller. The Challenge of Facts, and Other Essays. New Haven: Yale University Press, 1914.

Dyfyniad MLA

Sumner, William Graham, and Albert Galloway Keller. The Challenge of Facts, and Other Essays. Yale University Press, 1914.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.