@Article{ 
  bdapma99,
  author = { Dacorogna, Bernard and Marcellini, Paolo },
  title = { Implicit partial differential equations },
  journal = { Birkhauser, Boston },
  year = { 1999 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1351/ },
  note = { cvgmt preprint}
}