Yupeng Fu Yufei Xue Tong Zhu Yiqun Liu Min Zhang Shaoping Ma THUIR at TREC 2007: Enterprise Track. 2007 TREC http://trec.nist.gov/pubs/trec16/papers/tsinghuau-zhang.ent.final.pdf conf/trec/2007 db/conf/trec/trec2007.html#FuXZLZM07