db/conf/sigir/LosadaB99.html David E. Losada Alvaro Barreiro Using a Belief Revision Operator for Document Ranking in Extended Boolean Models. 66-73 SIGIR1999/P066.pdf 1999 conf/sigir/99 SIGIR http://doi.acm.org/10.1145/312624.312654 db/conf/sigir/sigir99.html#LosadaB99