@Misc{ 
  Bes22,
  author = { Beschastnyi, Ivan },
  title = { Closure of the Laplace-Beltrami operator on 2D almost-Riemannian manifolds and semi-Fredholm properties of differential operators on Lie manifolds },
  journal = {  },
  year = { 2022 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/5560/ },
  note = { cvgmt preprint}
}