@Misc{ 
  ArrSko19,
  author = { Arroyo-Rabasa, Adolfo and Skorobogatova, Anna },
  title = { On the fine properties of elliptic operators },
  journal = {  },
  year = { 2019 },
  pages = { 29 },
  URL = { http://cvgmt.sns.it/paper/4520/ },
  note = { cvgmt preprint}
}