RomanyukA. S. “The Best Trigonometric Approximations and the Kolmogorov Diameters of the Besov Classes of Functions of Many Variables”. Ukrains’kyi Matematychnyi Zhurnal 45, no. 5 (May 25, 1993): 663–675. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5853.