@Misc{ 
  sanvia08,
  author = { Santambrogio, Filippo and Vialard, François-Xavier },
  title = { A semi derivation lemma on BV functions },
  journal = {  },
  year = { 2008 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1384/ },
  note = { cvgmt preprint}
}