Ali Dasdan Chris Drome Santanu Kolay Micah Alpern Alice Han Tom Chi Jamie Hoover Ivan Davtchev Sharad Verma Thumbs-Up: a game for playing to rank search results. 36-37 2009 KDD Workshop on Human Computation http://doi.acm.org/10.1145/1600150.1600163 conf/kdd/2009hcomp db/conf/kdd/hcomp2009.html#DasdanDKAHCHDV09