Georgia Koutrika Zahra Mohammadi Zadeh Hector Garcia-Molina CourseCloud: summarizing and refining keyword searches over structured data. 1132-1135 2009 EDBT http://doi.acm.org/10.1145/1516360.1516496 conf/edbt/2009 db/conf/edbt/edbt2009.html#KoutrikaZG09a