Georgia Koutrika Benjamin Bercovitz Robert Ikeda Filip Kaliszan Henry Liou Hector Garcia-Molina Flexible Recommendations for Course Planning. 1467-1470 2009 ICDE http://doi.ieeecomputersociety.org/10.1109/ICDE.2009.127 conf/icde/2009 db/conf/icde/icde2009.html#KoutrikaBIKLG09