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2. B. Sz.-Nagy, “Sur les contractions de l’espace de Hilbert,” Acta Sci. Math., 15, 87–92 (1953).
3. N. K. Nikol’skii, Lectures on the Shift Operator [in Russian], “Nauka”, Moscow (1980).
4. N. K. Nikol'skii and S. V. Khrushchëv, "A functional model and some problems of the spectral theory of functions," Trudy Mat. Inst. Steklov, 176, 97-210 (1987)
5. English transl., Proc. Steklov Inst. Math., No. 3, 101-214 (1988).