@article{JMLR:v7:shalev-shwartz06a,
  author  = {Shai Shalev-Shwartz and Yoram Singer},
  title   = {Efficient Learning of Label Ranking by Soft Projections onto Polyhedra},
  journal = {Journal of Machine Learning Research},
  year    = {2006},
  volume  = {7},
  number  = {58},
  pages   = {1567--1599},
  url     = {http://jmlr.org/papers/v7/shalev-shwartz06a.html}
}