Combining Deduction by Certainty with the Power of Magic. - Helmut Schmidt; Nikolaus Steger; Ulrich Güntzer; Werner Kießling; Rüdiger Azone; Rudolf Bayer (DOOD, 1989)

Semantics and Efficient Compilation for Quantitative Deductive Databases. - Nikolaus Steger; Helmut Schmidt; Ulrich Güntzer; Werner Kießling (ICDE, 1989)