Vakarchuk SB, Shchitov AN. On some extremal problems in the theory of approximation of functions in the spaces $S^p,\quad 1 \leq p < \infty$. Ukr. Mat. Zhurn. [Internet]. 2006Mar.25 [cited 2024Sep.1];58(3):303-16. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/3455