Romanyuk, A. S., and V. S. Romanyuk. 2019. “Approximating Characteristics of the Classes of periodic multivariate Functions in the Space $B_{∞,1}$”. Ukrains’kyi Matematychnyi Zhurnal 71 (2), 271-82. https://umj.imath.kiev.ua/index.php/umj/article/view/1437.