title: the ccube constraint object-oriented database system. authors: alexander brodsky , pavel a. exarkhopoulo , victor e. segal , jia chen. venue: sigmod conference. year: 1999
title: description logics for semantic query optimization in object-oriented database systems. authors: domenico beneventano , sonia bergamaschi , claudio sartori. venue: acm transactions on database systems ( tods ). year: 2003