Tie-Yan Liu Hao Wan Tao Qin Zheng Chen Yong Ren Wei-Ying Ma Site abstraction for rare category classification in large-scale web directory. 1108-1109 2005 conf/www/2005si WWW (Special interest tracks and posters) http://doi.acm.org/10.1145/1062745.1062892 db/conf/www/www2005si.html#LiuWQCRM05