@Misc{ 
  ButCitSol25,
  author = { Buttazzo, Giuseppe and Cito, Simone and Solombrino, Francesco },
  title = { Relations between principal eigenvalue and torsional rigidity with Robin boundary conditions },
  journal = {  },
  year = { 2025 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/7469/ },
  note = { cvgmt preprint}
}