conf/vldb/91 Joseph Albert Algebraic Properties of Bag Data Types. 211-219 1991 VLDB db/conf/vldb/vldb91.html#Albert91 db/conf/vldb/Albert91.html VLDB91/P211.PDF conf/sigmod/CareyDV88 ... journals/cacm/Codd70 conf/pods/DayalGK82 journals/tois/FishmanBCCCDDHKLMNRS87 journals/tods/HammerM81 ... conf/vldb/KlausnerG85 journals/jacm/Klug82 conf/oodbs/ManolaD86 ... conf/pods/MumickFPR90 conf/sigmod/MumickFPR90 conf/vldb/MumickPR90 conf/oodbs/SchwarzCFLMMP86 journals/tods/Shipman81 journals/tods/StonebrakerWKH76 books/cs/Ullman88 books/cs/Ullman89 conf/sigmod/VandenbergD91