@Misc{ 
  CheMalYan19,
  author = { Cheng, Jih-Hsin and Malchiodi, Andrea and Yang, Paul },
  title = { On the Sobolev quotient of three-dimensional CR manifolds },
  journal = {  },
  year = { 2019 },
  pages = { 36 },
  URL = { http://cvgmt.sns.it/paper/4276/ },
  note = { cvgmt preprint}
}