@Article{ 
  butsan09,
  author = { Buttazzo, Giuseppe and Santambrogio, Filippo },
  title = { A Mass Transportation Model for the Optimal Planning of an Urban Region },
  journal = { Siam Review },
  year = { 2009 },
  volume = { 51 },
  number = { 3 },
  pages = { 593-610 },
  URL = { http://cvgmt.sns.it/paper/1015/ },
  note = { cvgmt preprint}
}