Cosmic crystallography: the hyperbolic isometries
  All orientation preserving isometries of the hyperbolic three-space are studied, and the probability density of conjugate pair separations for each isometry is presented. The study is relevant for the cosmic crystallography, and is the theoretical counterpart of the mean histograms arising from computer simulations of the isometries. 
A.F.F. Teixeira (Centro Brasileiro de Pesquisas Fisicas)