@Misc{ 
  Fig12a,
  author = { Figalli, Alessio },
  title = { Sobolev regularity for the Monge-Ampère equation, with application to the semigeostrophic equations },
  journal = {  },
  year = { 2012 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1898/ },
  note = { cvgmt preprint}
}