SerdyukA. S. (1997) “Estimates of the Kolmogorov widths for classes of infinitely differentiable periodic functions”, Ukrains’kyi Matematychnyi Zhurnal, 49(12), pp. 1700–1706. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5176 (Accessed: 1September2024).