Vakarchuk, S. B., and V. G. Doronin. 2010. “Best Mean Square Approximations by Entire Functions of Finite Degree on a Straight Line and Exact Values of Mean Widths of Functional Classes”. Ukrains’kyi Matematychnyi Zhurnal 62 (8), 1032–1043. https://umj.imath.kiev.ua/index.php/umj/article/view/2935.