Ramakrishna Varadarajan Vagelis Hristidis Louiqa Raschid Maria-Esther Vidal Luis Ibáñez Héctor Rodríguez-Drumond Flexible and efficient querying and ranking on hyperlinked data sources. 553-564 2009 EDBT http://doi.acm.org/10.1145/1516360.1516425 conf/edbt/2009 db/conf/edbt/edbt2009.html#VaradarajanHRVIR09