Brendan J. Frey Anitha Kannan Nebojsa Jojic Product Analysis: Learning to Model Observations as Products of Hidden Variables. 729-735 2001 conf/nips/2001 NIPS http://www-2.cs.cmu.edu/Groups/NIPS/NIPS2001/papers/psgz/AA40.ps.gz db/conf/nips/nips2001.html#FreyKJ01