Egon Börger Gerhard Jäger Hans Kleine Büning Michael M. Richter Computer Science Logic, 5th Workshop, CSL '91, Berne, Switzerland, October 7-11, 1991, Proceedings CSL Lecture Notes in Computer Science 626 Springer 1992 3-540-55789-X 0-387-55789-X https://doi.org/10.1007/BFb0023753 https://www.worldcat.org/oclc/70314577 db/conf/csl/csl91.html