Y. N. Subbotin and S. A. Telyakovskii, “On relative widths of classes of differentiable functions. II”, Ukr. Mat. Zhurn., vol. 62, no. 3, pp. 423–431, Mar. 2010, Accessed: Feb. 16, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/2877