@Misc{ 
  GlaOlb19,
  author = { Gladbach, Peter and Olbermann, Heiner },
  title = { Coarea formulae and chain rules for the Jacobian determinant in
  fractional Sobolev spaces },
  journal = {  },
  year = { 2019 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/4394/ },
  note = { cvgmt preprint}
}