@Misc{ 
  figvil,
  author = { Figalli, Alessio and Villani, Cédric },
  title = { An approximation lemma about the cut locus, with applications in optimal transport theory },
  journal = { Methods Appl. Anal. },
  year = { 2008 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/679/ },
  note = { cvgmt preprint}
}