Cosmic Crystallography of the Second Order
  The cosmic crystallography method of Lehoucq et al. [1] produces sharp peaks in the distribution of distances between the images of cosmic sources. But the method cannot be applied to universes with compact spatial sections of negative curvature. We apply to these a second order crystallographic effect, as evidenced by statistical parameters. 
H. V. Fagundes and E. Gausmann (Instituto de Fisica Teorica,   Universidade Estadual Paulista, Sao Paulo)