Chaitanya K. Baru Bertram Ludäscher Yannis Papakonstantinou Pavel Velikhov Victor Vianu Features and Requirements for an XML View Definition Language: Lessons from XML Information Mediation. 1998 QL http://www.w3.org/TandS/QL/QL98/pp/xmas.html db/conf/w3c/ql1998.html#BaruLPVV98