@inproceedings{modelingimagepatcheswithadirected,
  title = {Modeling image patches with a directed hierarchy of Markov random fields},
  author = {Simon Osindero and Geoffrey E. Hinton},
  year = {2007},
  booktitle = {NeurIPS 2007 12},
  url = {http://papers.nips.cc/paper/3279-modeling-image-patches-with-a-directed-hierarchy-of-markov-random-fields},
}