APA (7th ed.) Citation

Freeman, E., Robson, E., Sierra, K., & Bates, B. (2020). Head First design patterns: Building extensible and maintainable object-oriented software (Second edition.). O'Reilly.

Chicago Style (17th ed.) Citation

Freeman, Eric, Elisabeth Robson, Kathy Sierra, and Bert Bates. Head First Design Patterns: Building Extensible and Maintainable Object-oriented Software. Second edition. Cambridge: O'Reilly, 2020.

MLA (9th ed.) Citation

Freeman, Eric, et al. Head First Design Patterns: Building Extensible and Maintainable Object-oriented Software. Second edition. O'Reilly, 2020.