@Misc{ 
  fig07,
  author = { Figalli, Alessio },
  title = { A simple proof of the Morse-Sard Theorem in Sobolev Spaces },
  journal = { Proc. Amer. Math. Soc. },
  year = { 2007 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/975/ },
  note = { cvgmt preprint}
}