RomanyukA. S., and RomanyukV. S. “Approximating Characteristics of the Classes of periodic multivariate Functions in the Space $B_{∞,1}$”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 2 (February 25, 2019): 271-282. Accessed December 4, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1437.