Schafroth M R Phys. Rev.96 1149 (1955); Schafroth M R Phys. Rev.100 463 (1955); Schafroth M R, M R Schafroth, S T Butler, and J M Blatt Helv. Phys. Acta30 93 (1957); Russ. transl., Schafroth M R The Theory Of Superconductivity (IL, M., 1960) p. 62
Alexandrov A S, J Ranninger, and S Robaszkiewicz Phys. Rev.B33 4526 (1986); Alexandrov A S, J Ranninger, and S Robaszkiewicz L. N. Bulaevski&ibreve;, A. A. Sobyanin, And D. I. Khomski&ibreve;, Zh. Eksp. Teor. Fiz.87 1490 (1984)