conf/sigmod/77 Antonio L. Furtado Larry Kerschberg An Algebra of Quotient Relations. 1-8 1977 SIGMOD Conference db/conf/sigmod/sigmod77.html#FurtadoK77 http://doi.acm.org/10.1145/509404.509406 db/conf/sigmod/FurtadoK77.html SIGMOD77/P001.PDF journals/cacm/Codd70 persons/Codd72 ... ... conf/sigmod/ChamberlinB74 ... ... ... conf/pacific/Pecherer75 journals/cacm/SmithC75 ... ... journals/cacm/BoyceCKH75 conf/sigmod/Tsichritzis76 ... journals/tse/Reisner77 ...