Co-operative and frustration effects in novel perovskite-related phases S.G. Ebbinghaus, S. Riegg, T. Götzfried and A. Reller Eur. Phys. J. Special Topics, 180 (2009) 91-116 Published online: 11 June 2010 DOI: 10.1140/epjst/e2010-01213-4