@Article{ 
  antpra09,
  author = { Antonietti, Paola F. and Pratelli, Aldo },
  title = { Finite Element Approximation of the Sobolev Constant },
  journal = { Numer. Math. },
  year = { 2010 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/767/ },
  note = { cvgmt preprint}
}