@Article{ 
  CitMuk21,
  author = { Citti, Giovanna and Mukherjee, Shirsho },
  title = { Regularity of quasi-linear equations with Hormander vector fields of step two },
  journal = { Advances in Mathematics },
  year = { 2022 },
  doi = { 10.1016/j.aim.2022.108593 },
  pages = { 46 },
  URL = { http://cvgmt.sns.it/paper/5295/ },
  note = { cvgmt preprint}
}