1. S. B. Stechkin, “Estimation of the remainder of Taylor series for some classes of analytic functions,” Izv. Akad. Nauk SSSR, Ser. Mat., 17, No. 5, 462–472 (1953).
2. I. Meremelia and V. Savchuk, “Approximations of holomorphic functions by generalized Zygmund sums,” Cas. J. Appl. Math., Ecol. Econ., 1, No. 1, 70–81 (2013).
3. P. Butzer and J. R. Nessel, Fourier Analysis and Approximation, Birkhäuser, Basel (1971).
4. J. Bustamente, Bernstein Operators and Their Properties, Birkhäuser, Basel (2017).
5. A. Zygmund, “On the degree of approximation of functions by Fejér means,” Bull. Amer. Math. Soc., 51, 274–278 (1945).