A. S. Romanyuk, “Estimation of the Entropy Numbers and Kolmogorov Widths for the Nikol’skii–Besov Classes of Periodic Functions of Many Variables”, Ukr. Mat. Zhurn., vol. 67, no. 11, pp. 1540–1556, Nov. 2015, Accessed: Feb. 16, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/2088