KurylyakA. O., SkaskivO. B., and Shapovalovs’kaL. O. “Wiman-Type Inequality for Functions Analytic in a Polydisc”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 68, no. 1, Jan. 2016, pp. 78-86, https://umj.imath.kiev.ua/index.php/umj/article/view/1823.