Quenching of the Haldane gap in LiVSi2O6 and related compounds B. Pedrini, S. Wessel, J. L. Gavilano, H. R. Ott, S. M. Kazakov and J. Karpinski Eur. Phys. J. B, 55 3 (2007) 219-228 Published online: 21 February 2007 DOI: 10.1140/epjb/e2007-00056-0