Howard E. Shrobe Tom M. Mitchell Reid G. Smith Proceedings of the 7th National Conference on Artificial Intelligence. St. Paul, MN, August 21-26, 1988. 0-262-51055-3 AAAI Press / The MIT Press 1988 AAAI http://www.aaai.org/Conferences/AAAI/aaai88.php db/conf/aaai/aaai88.html