APA (7th ed.) Citation

Lewis, C. S. (1980). The Screwtape letters. Fortress Press.

Chicago Style (17th ed.) Citation

Lewis, C. S. The Screwtape Letters. Philadelphia: Fortress Press, 1980.

MLA (9th ed.) Citation

Lewis, C. S. The Screwtape Letters. Fortress Press, 1980.

Warning: These citations may not always be 100% accurate.