1. V. Ya. Kirpichenkov, Zh. Éksp. Teor. Fiz. 113, 1522 (1998) [JETP 86, 833 (1998)].
2. I. M. Lifshitz and V. Ya. Kirpichenkov, Zh. Éksp. Teor. Fiz. 77, 989 (1979) [Sov. Phys. JETP 50, 499 (1979)].
3. I. M. Lifshitz, S. A. Gredeskul, and L. A. Pastur, Introduction to the Theory of Disordered Systems, Pergamon, Oxford (1981) [Russ. orig., Nauka, Moscow (1982)].