Young-Min Kim Jean-François Pessiot Massih-Reza Amini Patrick Gallinari An extension of PLSA for document clustering. 1345-1346 2008 CIKM http://doi.acm.org/10.1145/1458082.1458271 conf/cikm/2008 db/conf/cikm/cikm2008.html#KimPAG08