1. Maintaining knowledge about temporal intervals;Allen,1981
2. A constraint representation and explanation facility for renal physiology;Asbell;MIT SM Thesis, Cambridge, MA,1982
3. A model-driven question-answering system for mixed-initiative computer-assisted instruction;Brown;IEEE Trans. Systems Man Cybernet,1973
4. Causality and Modern Science;Bunge,1979
5. Reasoning from incomplete knowledge;Collins,1975