James Bennett Charles Elkan Bing Liu Padhraic Smyth Domonkos Tikk KDD Cup and workshop 2007. 51-52 2007 9 SIGKDD Explorations 2 http://doi.acm.org/10.1145/1345448.1345459 db/journals/sigkdd/sigkdd9.html#BennettELST07