Makoto Nakatsuji Yasuhiro Fujiwara Akimichi Tanaka Toshio Uchiyama Ko Fujimura Toru Ishida Classical music for rock fans?: novel recommendations for expanding user interests. 949-958 2010 CIKM http://doi.acm.org/10.1145/1871437.1871558 conf/cikm/2010 db/conf/cikm/cikm2010.html#NakatsujiFTUFI10