@Article{ 
  Mag14b,
  author = { Magnani, Valentino },
  title = { A new differentiation, shape of the unit ball and perimeter measure },
  journal = {  Indiana Univ. Math. J. },
  year = { 2017 },
  volume = { 66 },
  number = { 1 },
  pages = { 183-204 },
  URL = { http://cvgmt.sns.it/paper/2519/ },
  note = { cvgmt preprint}
}