@inproceedings{aconcaveregularizationtechniqueforsparse,
  title = {A concave regularization technique for sparse mixture models},
  author = {Martin O. Larsson and Johan Ugander},
  year = {2011},
  booktitle = {NeurIPS 2011 12},
  url = {http://papers.nips.cc/paper/4430-a-concave-regularization-technique-for-sparse-mixture-models},
}