Bakhtin, A. K. “On the Product of Inner Radii of Symmetric Nonoverlapping Domains”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 11 (November 25, 1997): 1454–1464. Accessed April 11, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5145.