FedorenkoA. S. “Best<em class="a-Plus-plus">m</Em&gt;-Term Trigonometric Approximations of Classes of (Ψ, β)-Differentiable Functions of One Variable”. Ukrains’kyi Matematychnyi Zhurnal 52, no. 6 (June 25, 2000): 850–855. Accessed November 22, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4482.