Hilda Hardy Nobuyuki Shimizu Tomek Strzalkowski Ting Liu Xinyang Zhang G. Bowden Wise Cross-document summarization by concept classification. 121-128 2002 conf/sigir/2002 SIGIR http://doi.acm.org/10.1145/564376.564399 db/conf/sigir/sigir2002.html#HardySSTZW02