@Misc{ 
  LiSanWan13,
  author = { Li, Qi-Rui and Santambrogio, Filippo and Wang, Xu-Jia },
  title = { Regularity in Monge's mass transfer problem },
  journal = { J. Math. Pures et Appl. },
  year = { 2013 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/2124/ },
  note = { cvgmt preprint}
}