Myronyuk, V. V. “Trigonometric Approximations and Kolmogorov Widths of Anisotropic Besov Classes of Periodic Functions of Several Variables”.
Ukrains’kyi Matematychnyi Zhurnal 66, no. 8 (August 25, 2014): 1117–1132. Accessed April 7, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/2203.