Romanyuk AS. Estimates for Approximation Characteristics of the Besov Classes $B_ r^{p,θ}$ of Periodic Functions of Many Variables in the Space $L_q. I$. Ukr. Mat. Zhurn. [Internet]. 2001Sep.25 [cited 2024Nov.25];53(9):1224-31. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/4341