1. D. N. Clark: One dimensional perturbations of restricted shifts, J. Analyse Math. 25 (1972), 169?191.
2. J. B. Conway: Subnormal operators, Pitman, Boston-London-Melbourne, 1981.
3. M. S. Livsic: On a class of linear operators in Hilbert spaces, Mat. Sb. 19 (1946), 239?262.
4. M. S. Livsic: Isometric operators with equal deficiency indices, quasi-unitary operators, Mat. Sb. 26 (1950), 247?264.
5. J. G. Stampfli: One-dimensional perturbations of operators, Pacific J. Math. 115 (1984), 481?491.