@Misc{ 
  GavPis21,
  author = { Gavitone, Nunzia and Piscitelli, Gianpaolo },
  title = { A monotonicity result for the first Steklov-Dirichlet Laplacian
  eigenvalue },
  journal = {  },
  year = { 2021 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/5698/ },
  note = { cvgmt preprint}
}