@Article{ 
  Foc12,
  author = { Focardi, Matteo },
  title = { Vector-valued obstacle problems for non-local energies },
  journal = { Discr. Contin. Dyn. Syst. B },
  year = { 2012 },
  volume = { 17 },
  pages = { 487-507 },
  URL = { http://cvgmt.sns.it/paper/1717/ },
  note = { cvgmt preprint}
}