Colossal dielectric constants in transition-metal oxides P. Lunkenheimer, S. Krohns, S. Riegg, S.G. Ebbinghaus, A. Reller and A. Loidl Eur. Phys. J. Special Topics, 180 (2009) 61-89 Published online: 11 June 2010 DOI: 10.1140/epjst/e2010-01212-5