Stasyuk, S. A. “Kolmogorov Widths for Analogs of the Nikol’skii–Besov Classes With Logarithmic Smoothness”. Ukrains’kyi Matematychnyi Zhurnal 67, no. 11 (November 25, 2015): 1579-1584. Accessed May 3, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/2092.