@Misc{ 
  De Fig11,
  author = { De Philippis, Guido and Figalli, Alessio },
  title = { $W^{2,1}$ regularity for solutions of the Monge-Ampère equation },
  journal = { Invent. Math. },
  year = { 2012 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1695/ },
  note = { cvgmt preprint}
}