@Article{ 
  bergaz04,
  author = { Berchio, Elvise and Gazzola, Filippo },
  title = { Some remarks on biharmonic elliptic problems with positive, increasing and convex nonlinearities },
  journal = {  },
  year = { 2004 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/720/ },
  note = { cvgmt preprint}
}