David A. Evans Jeffrey Bennett Jesse Montgomery Victor Sheftel David A. Hull James G. Shanahan TREC 2004 HARD Track Experiments in Clustering. 2004 TREC http://trec.nist.gov/pubs/trec13/papers/clairvoyance.hard.pdf conf/trec/2004 db/conf/trec/trec2004.html#EvansBMSHS04