1. Amarel, S. (1968). On representation of problems of reasoning about actions. In Donald Michie, editor,Machine Intelligence 3, pages 131?171. Edinburgh University Press, Edinburgh, Scotland.
2. Buntine, W. (1990). Myths and legends in learning classification rules. InProceedings of AAAI-90. Morgan Kaufmann.
3. Cohen, W. (1990). Learning approximate control rules of high utility. InProceedings of ML90, pages 268?276.
4. Ellman, T. (1993). Abstraction by approximate symmetry. InProceedings of IJCAI-93, Chambery, France.
5. Fu, L-M. & Buchanan, B.G. (1985). Learning intermediate knowledge in constructing a hierarchical knowledge base. InProc. of IJCAI-85, pages 659?666, Los Angeles, CA, August 1985. IJCAI, Inc.