R. V. Podvysotskii, “Estimation of the product of inner radii of partially nonoverlapping domains”, Ukr. Mat. Zhurn., vol. 60, no. 7, pp. 1004–1008, Jul. 2008, Accessed: Dec. 05, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3218