Anoop Korattikara Balan Levi Boyles Max Welling Jingu Kim Haesun Park Statistical Optimization of Non-Negative Matrix Factorization. 128-136 2011 15 Journal of Machine Learning Research - Proceedings Track http://www.jmlr.org/proceedings/papers/v15/balan11a/balan11a.pdf db/journals/jmlr/jmlrp15.html#BalanBWKP11