Fumiko Harada Yosuke Nakagawa Hisashi Ishii Hiroyuki Yamahara Hiromitsu Shimakawa Navigating Users Based on Estimation of Interest Vectors with Utility Function. 47-53 2008 C5 http://doi.ieeecomputersociety.org/10.1109/C5.2008.8 conf/c5/2008 db/conf/c5/c5-2008.html#HaradaNIYS08