conf/sigmod/93 Waqar Hasan Michael L. Heytens Curtis P. Kolovson Marie-Anne Neimat Spyros Potamianos Donovan A. Schneider Papyrus GIS Demonstration. 554-555 1993 SIGMOD Conference db/conf/sigmod/sigmod93.html#HasanHKNPS93 http://doi.acm.org/10.1145/170035.171562 db/conf/sigmod/HasanHKNPS93.html SIGMOD93/P554.PDF ... ... conf/pdis/ConnorsHKNSW91 conf/sigmod/GangulyHK92 conf/pos/HasanK92 conf/ssd/KolovsonNP93 ... conf/pdis/SchneiderC93