APA (7th ed.) Citation

Gaarder, J. (1996). Sophie's world: A novel about the History of Philosophy. Phoenix.

Chicago Style (17th ed.) Citation

Gaarder, Jostein. Sophie's World: A Novel About the History of Philosophy. London: Phoenix, 1996.

MLA (9th ed.) Citation

Gaarder, Jostein. Sophie's World: A Novel About the History of Philosophy. Phoenix, 1996.

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