Akbash, K. S., and I. K. Matsak. “The Order Law of Large Numbers of the Marcinkiewicz - Zygmund”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 62, no. 12, Dec. 2010, pp. 1587-9, https://umj.imath.kiev.ua/index.php/umj/article/view/2984.