1. N.I. Akhiezer, A.M. Rybalko, ?On the continuous analogues of polinomials orthogonal on the unit circle? Ukranian Math. J., 20 (1968), 1, 3?24.
2. F.V. Atkinson,Discrete and continuous boundary problems Academic Press, New York, London, 1964.
3. H.L. Cycon, R.G. Froese, W. Kirsh, B. Simon,Schr�dinger operators, with applications to quantum mechanics and global geometry. Springer-Verlag, Berlin, New-York, 1987.
4. Y.L. Geronimus.Polinomilas orthogonal on the unit circle, (in Russian), 1958.
5. M.G. Krein, ?Continuous analogues of propositions on polynomials orthogonal on the unit circle? Dokl. Akad. Nauk SSSR, 105 (1955), 637?640.