Jun Xu Jing Yao Jiaqian Zheng Qi Sun Junyu Niu WIM at TREC 2007. 2007 TREC http://trec.nist.gov/pubs/trec16/papers/fudan-niu.spam.ent.legal.geo.final.pdf conf/trec/2007 db/conf/trec/trec2007.html#XuYZSN07