1. L. P. Gor’kov, Zh. Éksp. Teor. Fiz. 37, 1407 (1959) [Sov. Phys. JETP 10, 998 (1959)].
2. N. R. Werthamer, in Superconductivity, Ed. by R. D. Parks (Marcel Dekker, New York, 1969), Vol. 1, p. 321.
3. S. V. Shulga and S. L. Drechsler, J. Low Temp. Phys. 129, 93 (2002).
4. L. P. Gor’kov and T. K. Melik-Barkhudarov, Zh. Éksp. Teor. Fiz. 45, 1493 (1963) [Sov. Phys. JETP 18, 1031 (1963)].
5. A. I. Golovashkin and N. P. Shabanova, Physica C (Amsterdam) 185–189, 2709 (1991).