Derev’yankoN. V. (2012) “Trigonometric widths of classes of periodic functions of many variables”, Ukrains’kyi Matematychnyi Zhurnal, 64(8), pp. 1041-1052. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/2639 (Accessed: 21November2024).