APA (7th ed.) Citation

Rohmer, S. (1960). The day the world ended. Ace Books.

Chicago Style (17th ed.) Citation

Rohmer, Sax. The Day the World Ended. New York, N.Y.: Ace Books, 1960.

MLA (9th ed.) Citation

Rohmer, Sax. The Day the World Ended. Ace Books, 1960.