Rudolf K. Keller Richard Lajoie Nazim H. Madhavji Tilmann F. W. Bruckhaus Kamel Toubache Won-Kook Hong Khaled El Emam 78-88 1993 ICSE http://portal.acm.org/citation.cfm?id=257572.257595 db/conf/icse/icse93.html#KellerLMBTHE93