@INPROCEEDINGS{BHS93,
   AUTHOR        = {Bernhard Beckert and Reiner H\"{a}hnle and
		    Peter H. Schmitt},
   TITLE         = {The Even More Liberalized $\delta$-Rule in Free Variable
                    Semantic Tableaux},
   BOOKTITLE     = {3rd Kurt G\"{o}del Colloquium ({KGC})},
   PLACE         = {Brno, Czech Republic},
   EDITOR        = {G. Gottlob and A. Leitsch and D. Mundici},
   PUBLISHER     = {Springer},
   SERIES        = {LNCS},
   VOLUME        = {713},		 
   PAGES         = {108--119},
   MONTH         = aug,
   YEAR          = {1993}
}