Romanyuk AS. Trigonometric widths of the classes $B_{p,θ}^ r$ of functions of many variables in the space $L_q$. Ukr. Mat. Zhurn. [Internet]. 1998Aug.25 [cited 2024Nov.24];50(8):1089-97. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/4858