@Misc{ 
  figrifvil09,
  author = { Figalli, Alessio and Rifford, Ludovic and Villani, Cédric },
  title = { On the Ma-Trudinger-Wang curvature on surfaces },
  journal = { Calc. Var. Partial Differential Equations },
  year = { 2010 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1529/ },
  note = { cvgmt preprint}
}