Hadhami Dhraief Alfons Kemper Wolfgang Nejdl Christian Wiesner Processing and Optimization of Complex Queries in Schema-Based P2P-Networks. 31-45 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3367&spage=31 2004 conf/dbisp2p/2004 DBISP2P db/conf/dbisp2p/dbisp2p2004.html#DhraiefKNW04