Koval T. L. “Estimation of the Convergence Rate in Central Limiting Theorem for Two-Parametric Martingale-Differences ”. Ukrains’kyi Matematychnyi Zhurnal 44, no. 8 (September 8, 1992): 1138-1141. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/8049.