SavchukV. V. “Best Linear Methods of Approximation of Functions of the Hardy Class $H_p$”. Ukrains’kyi Matematychnyi Zhurnal 55, no. 7 (July 25, 2003): 919-925. Accessed November 25, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3967.