APA (7th ed.) Citation

Lewis, C. S. (1944). The Screwtape letters. Macmillan Co.

Chicago Style (17th ed.) Citation

Lewis, Clive Staples. The Screwtape Letters. New York: Macmillan Co, 1944.

MLA (9th ed.) Citation

Lewis, Clive Staples. The Screwtape Letters. Macmillan Co, 1944.