Nuno Cardoso Mário J. Silva Bruno Martins The University of Lisbon at CLEF 2006 Ad-Hoc Task. 51-56 2006 conf/clef/2006 CLEF http://dx.doi.org/10.1007/978-3-540-74999-8_6 db/conf/clef/clef2006.html#CardosoSM06