Bakhtin , A. K., and Ya. V. Zabolotnii. “Estimates of the Products of Inner Radii for Multiconnected Domains”. Ukrains’kyi Matematychnyi Zhurnal 73, no. 1 (January 22, 2021): 9 - 22. Accessed April 20, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/6200.