1. F.G. Bass, A.A. Bulgakov, A.P. Tetervov, High-Frequency Properties of Semiconductors With Superlattices, Nauka, Moscow, 1989, in Russian.
2. L.P. Gor'kov, G.M. Eliashberg, Zh. Eksp. Teor. Fiz. 54 (1968) 612. [Sov. Phys. JETP 27 (1968) 328].
3. A.M. Gulian, G.F. Zharkov, Superconductors in External Fields, Nauka, Moscow, 1989, in Russian.