@article{JMLR:v7:heiler06a,
  author  = {Matthias Heiler and Christoph Schn{{\"o}}rr},
  title   = {Learning Sparse Representations by Non-Negative Matrix Factorization and Sequential Cone Programming},
  journal = {Journal of Machine Learning Research},
  year    = {2006},
  volume  = {7},
  number  = {51},
  pages   = {1385--1407},
  url     = {http://jmlr.org/papers/v7/heiler06a.html}
}