@article{Abramowicz:2005,
  author  = "M. Abramowicz and W. Klužniak",
  title   = "Epicyclic frequencies derived from the effective potential : simple and practical formulae",
  journal = "Astrophysics and Space Science",
  volume  = "Vol. 300",
  number  = "no 1-3",
  pages   = "127--136",
  year    = "2005",
}