@workingPaper{AchillesHollunderLauxMohren_1991, title={KRIS : knowledge representation and inference system - Benutzerhandbuch -}, author={Achilles, Erich and Hollunder, Bernhard and Laux, Armin and Mohren, Jörg-Peter}, doi={http://dx.doi.org/10.22028/D291-25246}, year={1991} }