1. Objects and views;Abiteboul,1991
2. Object identity as a query language primitive;Abiteboul,1989
3. Efficient optimization of a class of relational expressions;Aho;ACM Transactions on Database Systems,1979
4. A query language for O2;Bancilhon,1992
5. Foundations of semantic query optimization for deductive databases;Chakravarthy,1988