Vakarchuk, S. B. “On the Estimates of Widths of the Classes of Functions Defined by the generalized moduli of Continuity and Majorants in the Weighted Space $L_{2x} (0,1)$”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 71, no. 2, Feb. 2019, pp. 179-8, https://umj.imath.kiev.ua/index.php/umj/article/view/1430.