@Misc{ 
  San11a,
  author = { Santambrogio, Filippo },
  title = { A Modest Proposal for MFG with Density Constraints },
  journal = { proceedings of the workshop "Mean Field Games and related topics", Rome, May 2011 },
  year = { 2011 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1679/ },
  note = { cvgmt preprint}
}