@INPROCEEDINGS{HustadtNonnengart93,
 AUTHOR        = {Hustadt, Ullrich and Nonnengart, Andreas},
 TITLE         = {Modalities in Knowledge Representation},
 BOOKTITLE     = {Proceedings of the 6th Australian Joint Conference 
on Artificial Intelligence},
 PAGES         = {249--254},
 EDITOR        = {Rowles, Chris and Liu, Huan and Foo, Norman},
 MONTH         = {16--19~} # nov ,
 ADDRESS       = {Melbourne, Australia},
 YEAR          = {1993},
 PUBLISHER     = {World Scientific},
}