@Misc{ 
  figrif09,
  author = { Figalli, Alessio and Rifford, Ludovic },
  title = { Mass Transportation on Sub-Riemannian Manifolds },
  journal = { Geom. Funct. Anal. },
  year = { 2009 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/897/ },
  note = { cvgmt preprint}
}