@Misc{ 
  cara,
  author = { Caravenna, Laura },
  title = { An existence result for the Monge problem in $R^n$ with norm cost functions },
  journal = {  },
  year = { 2009 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1303/ },
  note = { cvgmt preprint}
}