APA (7th ed.) Citation

Koster, R. (2013). A theory of fun: For game design (2a. ed.). O'Reilly Media.

Chicago Style (17th ed.) Citation

Koster, Raph. A Theory of Fun: For Game Design. 2a. ed. Sebastopol: O'Reilly Media, 2013.

MLA (9th ed.) Citation

Koster, Raph. A Theory of Fun: For Game Design. 2a. ed. O'Reilly Media, 2013.

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