1. N. I. Akhieser and I. M. Glazman, Theory of Linear Operators in Hilbert Space, Pitman (Advanced Publishing Program), Boston, Mass.-London (1980).
2. D. Z. Arov and I. P. Gavrilyuk, “A method for solving initial value problems for linear differential equations in Hilbert space based on the Cayley transform,” Numer. Funct. Anal. Optim., 14, No. 5-6, 456–473 (1993).
3. A. Ashyralyev, “A note on fractional derivatives and fractional powers of operators,” J. Math. Anal. Appl., 357, No. 1, 232–236 (2009).
4. D. Z. Arov, I. P. Gavrilyuk, and V. L. Makarov, “Representation and approximation of solution of initial value problems for differential equations in Hilbert space based on the Cayley transform,” Elliptic and parabolic problems (Pont-`a-Mousson, 1994), Pitman Res. Notes Math. Ser., 325, 40–50 (1995).
5. H. Bateman and A. Erdelyi, Higher Transcendental Functions, Vol. 2, MC Graw-Hill Book Co., New York–Toronto–London (1988).