Citazione APA

Gaarder, J. (1996). Sophie's world: A novel about the history of philosophy. Penguin Group.

Stile di citazione Chicago

Gaarder, Jostein. Sophie's World: A Novel About the History of Philosophy. New York: Penguin Group, 1996.

Citazione MLA

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