1. Inductive learning of decision rules with exceptions: methodology and experimentation;Becker,1985
2. On inheritance hierarchies with exceptions;Etherington,1983
3. Description and theoretical analysis (using schemata) of PLANNER: A language for proving theorems and manipulating models in a robot;Hewitt;Ph.D. Thesis, MIT AI Laboratory, TR-258,1972
4. Circumscription—A form of non-monotonic reasoning;McCarthy;Artificial Intelligence,1980