1. SHELXS 86, Program for Crystal Structure Determination, Universit�t G�ttingen, 1986.
2. SHELXL 93, Program for Crystal Structure Refinement, Universit�t G�ttingen, 1993.
3. SCHAKAL 92 (Program for graphic representation of crystal structures), Universit�t Freiburg, 1992.
4. Effective coordination numbers (ECoN) and mean Active fictive ionic radii (MEFIR)[1,2]*