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3. J.H. Slater: Quantum Theory of Molecules and Solids, Vol. 2 ( McGraw-Hill, New York 1965 )
4. J.F. Annett: Adv. in Phys. 39, 83 (1990)
5. H. Ibach, H. Lüth: Solid-State Physics, 2nd edn. ( Springer, Berlin, Heidelberg 1995 )