@Misc{ 
  ambgig11,
  author = { Ambrosio, Luigi and Gigli, Nicola },
  title = { A user's guide to optimal transport },
  journal = {  },
  year = { 2011 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/195/ },
  note = { cvgmt preprint}
}