- Wikipedia has a good article on design patterns.
- The C2 Wiki is another good place to look for information about design patterns like observer, singleton, and more.
- The original Design Patterns book is a must-read for any engineer.
- O'Reilly's Head First Design Patterns is a lighter-weight way to get into design patterns.
- The book PHP Hacks has several hacks for design patterns that extend beyond the examples shown here.
- See the developerWorks article "Five more PHP design patterns" to learn about five additional design patterns that you