@Misc{ 
  Pas13,
  author = { Passarelli di Napoli, Antonia },
  title = { Higher differentiability of solutions of  elliptic systems with Sobolev coefficients: the case p=n=2 },
  journal = {  },
  year = { 2013 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/2132/ },
  note = { cvgmt preprint}
}