@Misc{ 
  belbeopaob,
  author = { Bellettini, Giovanni and Beorchia, Valentina and Paolini, Maurizio },
  title = { Completeness of Reidemeister-type moves for surfaces embedded in three-dimensional space },
  journal = {  },
  year = { 2009 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/501/ },
  note = { cvgmt preprint}
}