Giorgos Kokkinidis Vassilis Christophides Semantic Query Routing and Processing in P2P Database Systems: The ICS-FORTH SQPeer Middleware. 486-495 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3268&spage=486 2004 conf/edbtw/2004 EDBT Workshops db/conf/edbtw/edbtw2004.html#KokkinidisC04