Serdyuk, A.S., and I.V. Sokolenko. “Asymptotic Estimates for the Widths of Classes of Functions of High Smothness”. Carpathian Mathematical Publications 15, no. 1 (June 30, 2023): 246–259. Accessed May 13, 2024. https://journals.pnu.edu.ua/index.php/cmp/article/view/6705.