Mark A. Greenwood Mark Stevenson Robert J. Gaizauskas The University of Sheffield's TREC 2006 Q&A Experiments. 2006 TREC http://trec.nist.gov/pubs/trec15/papers/usheffield.qa.final.pdf conf/trec/2006 db/conf/trec/trec2006.html#GreenwoodSG06