Bushev, D. M. and Koval’chuk, I. R. (1993) “On approximation of convolution classes”, Ukrains’kyi Matematychnyi Zhurnal, 45(1), pp. 26–31. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5778 (Accessed: 2June2024).