@Article{ 
  BilMer14,
  author = { Biliotti, Leonardo and Mercuri, Francesco },
  title = { Properly discontinuous actions on Hilbert manifolds’ },
  journal = { Bull. Braz. Math. Soc. (N.S.) },
  year = { 2014 },
  doi = { 10.1007/s00574-014-0057-7 },
  volume = { 45 },
  number = { 3 },
  pages = { 433-452 },
  URL = { https://gecogedi.dimai.unifi.it/paper/16/ },
  note = { cvgmt preprint}
}