Myronyuk, V. V. “Widths of the Anisotropic Besov Classes of Periodic Functions of Several Variables”. Ukrains’kyi Matematychnyi Zhurnal 68, no. 8 (August 25, 2016): 1080–1091. Accessed February 16, 2026. https://umj.imath.kiev.ua/index.php/umj/article/view/1903.