1. Lecture Notes in Physics;CRA Catlow,1982
2. NATO ASI Series C;CRA Catlow,1997
3. Callow, C.R.A. (1997) Computer Modelling in Inorganic Crystallography, Academic Press, New York, NY.
4. Winkler, B., Milman, V., and Payne, M.C. (1995) Miner. Mag., 59, 589.
5. Madelung, E. (1918) Phys. Zeit. 19, 524.