Kenta Oku Shinsuke Nakajima Jun Miyazaki Shunsuke Uemura Hirokazu Kato A recommendation method considering users' time series contexts. 465-470 2009 ICUIMC http://doi.acm.org/10.1145/1516241.1516321 conf/icuimc/2009 db/conf/icuimc/icuimc2009.html#OkuNMUK09