Abdullayev, F., Anatolii Serdyuk, and A. Shidlich. “Widths of Functional Classes Defined by Majorants of Generalized Moduli of Smoothness in the Spaces ${\mathcal S}^{p}$”.
Ukrains’kyi Matematychnyi Zhurnal 73, no. 6 (June 18, 2021): 723–737. Accessed April 11, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/6432.