Tetsuya Sakai Makoto Koyama Tatsuya Izuha Akira Kumano Toshihiko Manabe Tomoharu Kokubu Toshiba BRIDJE at NTCIR-6 CLIR: The Head/Lead Method and Graded Relevance Feedback. 2007 NTCIR http://research.nii.ac.jp/ntcir/workshop/OnlineProceedings6/NTCIR/9.pdf conf/ntcir/2007 db/conf/ntcir/ntcir2007.html#SakaiKIKMK07