@Misc{ 
  AndTio26,
  author = { André, Guerra and Tione, Riccardo },
  title = { Constancy of the index for gradient mappings },
  journal = {  },
  year = { 2026 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/7587/ },
  note = { cvgmt preprint}
}