1.
Voitenko SP. Best orthogonal trigonometric approximations of the classes $B^{Ω}_{p,θ}$ of periodic functions of many variables. Ukr. Mat. Zhurn. [Internet]. 2009Nov.25 [cited 2024Apr.26];61(11):1473-84. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/3115