V. V. Myronyuk, “Widths of the anisotropic Besov classes of periodic functions of several variables”, Ukr. Mat. Zhurn., vol. 68, no. 8, pp. 1080–1091, Aug. 2016, Accessed: Feb. 16, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/1903