1. T. Koritsánszky, R. Flaig, D. Zobel, P. Luger, Institute for Crystallography, Free University of Berlin, Takustrasse 6, 14195 Berlin, Germany.
2. H.-G. Krane, Institute for Mineralogy and Petrography, University of Bonn, Poppelsdorfer Schloss, 53115 Bonn, Germany.
3. W. Morgenroth, Institute for Mineralogy and Petrography, University of Hamburg, Grindelallee 48, 20146 Hamburg, Germany.