Stepanets, O. I. “Rate of Convergence of a Group of Deviations on Sets of $\bar{\psi}$−integrals”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 51, no. 12, Dec. 1999, pp. 1673-9, https://umj.imath.kiev.ua/index.php/umj/article/view/4771.