title: lockx : a system for efficiently querying secure xml. authors: sungran cho , laks v. s. lakshmanan , divesh srivastava , sihem amer-yahia. venue: sigmod conference. year: 2003
title: genesys : a system for efficient spatial query processing. authors: thomas brinkhoff , hans-peter kriegel , ralf schneider , bernhard seeger. venue: international conference on management of data. year: 1994