APA (7th ed.) Citation

Gamma, E., Helm, R., Johnson, R., & Vlissides, J. (1994). Design Patterns: Elements of Reusable Object-Oriented Software (1st edition.). Addison-Wesley Professional.

Chicago Style (17th ed.) Citation

Gamma, Erich, Richard Helm, Ralph Johnson, and John Vlissides. Design Patterns: Elements of Reusable Object-Oriented Software. 1st edition. Addison-Wesley Professional, 1994.

MLA (9th ed.) Citation

Gamma, Erich, et al. Design Patterns: Elements of Reusable Object-Oriented Software. 1st edition. Addison-Wesley Professional, 1994.