Lucian Vlad Lita Jaime G. Carbonell Cluster-Based Selection of Statistical Answering Strategies. 1653-1658 2007 conf/ijcai/2007 IJCAI http://dli.iiit.ac.in/ijcai/IJCAI-2007/PDF/IJCAI07-267.pdf db/conf/ijcai/ijcai2007.html#LitaC07