Zherebko, T. M. “On the Polynomial Approximation of a Conformal Mapping of a Domain With Nonzero Corner”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 63, no. 9, Sept. 2011, pp. 1285-9, https://umj.imath.kiev.ua/index.php/umj/article/view/2805.