Lingpeng Yang Dong-Hong Ji Guodong Zhou Nie Yu Guozheng Xiao Document re-ranking using cluster validation and label propagation. 690-697 2006 conf/cikm/2006 CIKM http://doi.acm.org/10.1145/1183614.1183713 db/conf/cikm/cikm2006.html#YangJZNX06