Derev’yanko, N. V. (2014). Approximation of the Classes $H_p^{Ω}$ of Periodic Functions of Many Variables in the Space $L_p$.
Ukrains’kyi Matematychnyi Zhurnal
,
66
(5), 634–644.
https://umj.imath.kiev.ua/index.php/umj/article/view/2165