1. C. Kittel: Introduction to Solid State Physics, 5th ed. ( Wiley and Sons, New York 1976 )
2. C. Kittel: Quantum Theory of Solids ( Wiley and Sons, New York 1973 )
3. J.M. Ziman: Principles of the Theory of Solids ( Cambridge University Press, London 1964 )
4. J.C. Slater, G.F. Koster: Phys. Rev. 94, 1498 (1954)
5. T. Morita: J. Math. Phys. 12, 1744 (1971)