@article{JMLR:v17:15-151,
  author  = {Andrew M. McDonald and Massimiliano Pontil and Dimitris Stamos},
  title   = {New Perspectives on k-Support and Cluster Norms},
  journal = {Journal of Machine Learning Research},
  year    = {2016},
  volume  = {17},
  number  = {155},
  pages   = {1--38},
  url     = {http://jmlr.org/papers/v17/15-151.html}
}