@Misc{ 
  Afe23,
  author = { Afeltra, Claudio },
  title = { Rectifiability of sets of solutions of first order systems of partial differential equations },
  journal = {  },
  year = { 2023 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/6190/ },
  note = { cvgmt preprint}
}