@InCollection{Lee+etal08:sparseDBN,
	title = {Sparse Deep Belief Net Model for Visual Area {V2}},
	author = {Honglak Lee and Chaitanya Ekanadham and Andrew~Y. Ng},
	booktitle = {Advances in Neural Information Processing Systems 20},
	pages = {873--880},
	year = {2008}
}