1. Blatt F. J., Physics of Electronics Conductions in Solids. McGraw-Hill Book Company, 1968.
2. Geygen M. F., Pekar S. I., Zh. Exp. Teor. Fiz.21 (1951), 803.
3. Erezhenov M. E., Pekar S. I., Fiz. Tverd. Tela5 (1963), 1297.
4. Pekar S. I., Fiz. Tverd. Tela8 (1966), 1115.
5. Herring C., J. Appl. Phys.31 (1960), 1939.