1. Chambers, C.: Object-Oriented Multi-Methods in Cecil, Proc.ECOOP’92.
2. Chambers, C.: Predicate Classes, Proc.ECOOP’93.
3. Ernst, M., Kaplan, C., and Chambers, C.: Predicate Dispatching: A Unified Theory of Dispatch, ECOOP’98.
4. Harada, Y., Yamazaki, K.: Condition Classes: Polymorphism and Inheritance without Data Abstraction, PRO, IPSJ, Jan. 1996 (In Japanese).
5. Steele, G.L.: Common Lisp: The Language, Digital Press, Bedford MA, 1990. Second edition.