Structural investigations of the tetraborates MB4O7 (M = Pb, Sr, Ba) W.-D. Stein, J. Liebertz, P. Becker, L. Bohatý and M. Braden Eur. Phys. J. B, 85 7 (2012) 236 Published online: 05 July 2012 DOI: 10.1140/epjb/e2012-21062-y