APA (7th ed.) Citation

Spengler, O. (1944). The decline of the west (5. printing.). Knopf.

Chicago Style (17th ed.) Citation

Spengler, Oswald. The Decline of the West. 5. printing. New York: Knopf, 1944.

MLA (9th ed.) Citation

Spengler, Oswald. The Decline of the West. 5. printing. Knopf, 1944.