@article{Pani:20090R,
  author = "Pani, Paolo  and  Cardoso, V.  and  Cadoni, Mariano  and  Cavaglià, Marco",
  title = "{Ergoregion instability rules out black hole doubles}",
  doi = "10.22323/1.075.0027",
  journal = "PoS",
  year = 2009,
  volume = "BHs, GR and Strings",
  pages = "027"
}