A Modified Relational Algebra and its Use in an Entity-Relationship Environment.

Victor M. Markowitz Yoav Raz A Modified Relational Algebra and its Use in an Entity-Relationship Environment. 315-328 1983 ER db/conf/er/er83.html#MarkowitzR83 conf/er/83 er83/ER83-P315.pdf conf/er/AtzeniC81 journals/tods/Chen76 persons/Codd72 journals/cacm/Codd82 journals/is/Furtado78 conf/ds/HallOT76 ... journals/jacm/Klug82 conf/er/MarkowitzR83a ... ... journals/sigmod/Pirotte82 conf/er/SantosNF79 ...