@conference {diego_13_learning2,
	title = {Learning Multi-Level Sparse Representation},
	booktitle = {NIPS. Proceedings},
	year = {2013},
	note = {1},
	url = {http://papers.nips.cc/paper/5076-learning-multi-level-sparse-representations},
	author = {Ferran Diego and Fred A. Hamprecht}
}
