Extensions of Logic Programming International Workshop, Tübingen, FRG, December 8-10, 1989. Proceedings Schroeder-Heister Peter Heftet / 1991 / Engelsk
Extensions of Logic Programming 5th International Workshop, ELP '96, Leipzig, Germany, March 28 - 30, 1996. Proceedings. Dyckhoff Roy Heftet / 1996 / Engelsk
Proof Theory in Computer Science International Seminar, PTCS 2001 Dagstuhl Castle, Germany, October 7-12, 2001. Proceedings Kahle Reinhard Heftet / 2001 / Engelsk
Logic, Methodology and Philosophy of Science. Logic and Science Facing the New Technologies Schroeder-Heister Peter Heftet / 2015 / Engelsk
Extensions of Logic Programming Second International Workshop, ELP '91, Stockholm, Sweden, January 27-29, 1991. Proceedings Eriksson Lars-Henrik Heftet / 1992 / Engelsk
