N. V. Derev’yanko, “Approximation of the Classes $H_p^{Ω}$ of Periodic Functions of Many Variables in the Space $L_p$”, Ukr. Mat. Zhurn., vol. 66, no. 5, pp. 634–644, May 2014, Accessed: Apr. 13, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/2165