@Misc{ 
  dongiagre05,
  author = { D'Onofrio, Luigi and Giannetti, Flavia and Greco, Luigi },
  title = { On Weak Hessian Determinants },
  journal = {  },
  year = { 2005 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1245/ },
  note = { cvgmt preprint}
}