Kaushik Chakrabarti Michael Ortega-Binderberger Sharad Mehrotra Kriengkrai Porkaew Evaluating Refined Queries in Top-k Retrieval Systems. 256-270 2004 16 IEEE Trans. Knowl. Data Eng. 2 http://csdl.computer.org/comp/trans/tk/2004/02/k0256abs.htm db/journals/tkde/tkde16.html#ChakrabartiOMP04