Progress in Mathematical Relativity, Gravitation and Cosmology Proceedings of the Spanish Relativity Meeting ERE2012, University of Minho, Guimarães, Portugal, September 3-7, 2012 - García-Parrado, Alfonso; Mena, Filipe C.; Moura, Filipe; Vaz, Estelita (Springer Berlin Heidelberg : Imprint: Springer, 2014)