1. e.g.: Gilchrist, J. le, Monceau, M.: J. Phys. C3, 1399 (1970)
2. Piosczyk, P., Kneisel, P., Stoltz, O., Halbritter, J.: IEEE Trans.NS-20 No. 3, 108 (1973)
3. Bardeen, J., Cooper, L.N., Schrieffer, J.R.: Phys. Rev.108, 1175 (1957)
4. Abrikosov, A. A., Gorkov, L. P., Dzyaloshinskii, I. Yu.: Quantum field theoretical methods in statistical physics. New York: Pergamon Press 1965
5. Khalatnikov, I.M., Abrikosov, A.A.: Advan. Phys.8, 45 (1958)