title: the mlpq/gis constraint database system. authors: yuguo liu , yiming li , pradip kanjamala , rui chen , yonghui wang , peter z. revesz. venue: sigmod conference. year: 2000
title: metu interoperable database system. authors: asuman dogac , ugur halici , ebru kilic , gokhan ozhan , fatma ozcan , sena nural , cevdet dengi , sema mancuhan , budak arpinar , pinar koksal , cem evrendilek. venue: international conference on management of data. year: 1996