title: optimizing queries with universal quantification in object-oriented and object-relational databases. authors: j clauпen , a kemper , g moerkotte , k peithner. venue: vldb. year: 1997
title: queries and query processing in object-oriented database systems. authors: dd straube , mt ã?zsu. venue: acm transactions on information systems ( tois ) ,. year: 1990.0