1. R.A. Evarestov, V.P. Smirnov, Site Symmetry in Crystals: Theory and Applications, 2nd edn. Springer Series in Solid State Sciences, vol. 108 (Springer, Berlin, 1997)
2. V.R. Saunders, R. Dovesi, C. Roetti, R. Orlando, C.M. Zicovich-Wilson, N.M. Harrison, CRYSTAL-2003 Users Manual (University of Torino, Torino, 2003).
http://www.crystal.unito.it
3. T. Bredow, G. Geudtner, K. Jug, J. Comput. Chem. 22, 861 (2001)
4. P. Deak, Phys. Stat. Sol. (b) 217, 9 (2000)
5. B. Silvi, N. Fouranti, R. Nada, C.R. Catlow, J. Phys. Chem. Solids 52, 1005 (1991)