title: a query language for multidimensional arrays : design , implementation , and optimization techniques. authors: limsoon wong , rona machlin , leonid libkin. venue: sigmod conference. year: 1996
title: implementation of two semantic query optimization techniques in db2 universal database. authors: qi cheng , jarek gryz , fred koo , t. y. cliff leung , linqi liu , xiaoyan qian , k. bernhard schiefer. venue: very large data bases. year: 1999