RomanyukA. S. (1993) “The best trigonometric approximations and the Kolmogorov diameters of the Besov classes of functions of many variables”, Ukrains’kyi Matematychnyi Zhurnal, 45(5), pp. 663–675. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5853 (Accessed: 27July2024).