@Article{ 
  BarDra13,
  author = { Bardi, Martino and Dragoni, Federica },
  title = { Subdifferential and Properties of  Convex Functions with respect to Vector Fields },
  journal = { J. Convex Analysis },
  year = { 2014 },
  volume = { 21 },
  number = { 3 },
  pages = { 785--810 },
  URL = { http://cvgmt.sns.it/paper/2201/ },
  note = { cvgmt preprint}
}