BozhukhaL. N. (2003) “On a Jackson-Type Inequality in the Approximation of a Function by Linear Summation Methods in the Space $L_2$”, Ukrains’kyi Matematychnyi Zhurnal, 55(4), pp. 537-545. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/3927 (Accessed: 27July2024).