Voitsekhivs’kyi, V. R. “Jackson-Type Inequalities in the Space $S^p$”. Ukrains’kyi Matematychnyi Zhurnal 55, no. 9 (September 25, 2003): 1167-1177. Accessed May 18, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3990.