RomanyukA. S. “Entropy Numbers and the Widths of the Classes $B_{p,θ}^r$ of Periodic Functionsof Many Variables”. Ukrains’kyi Matematychnyi Zhurnal 68, no. 10 (October 25, 2016): 1403-1417. Accessed November 23, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1928.