Ariel Fuxman Mauricio A. Hernández C. T. Howard Ho Renée J. Miller Paolo Papotti Lucian Popa Nested Mappings: Schema Mapping Reloaded. 67-78 2006 conf/vldb/2006 VLDB http://www.vldb.org/conf/2006/p67-fuxman.pdf db/conf/vldb/vldb2006.html#FuxmanHHMPP06