Alessandro Raffio Daniele Braga Stefano Ceri Paolo Papotti Mauricio A. Hernández Clip: a tool for mapping hierarchical schemas. 1271-1274 2008 SIGMOD Conference http://doi.acm.org/10.1145/1376616.1376753 conf/sigmod/2008 db/conf/sigmod/sigmod2008.html#RaffioBCPH08