Bakhtin, O. K., and I. V. Denega. “Estimation of the Maximum Product of Inner Radii of Mutually Disjoint Domains”.
Ukrains’kyi Matematychnyi Zhurnal
, vol. 72, no. 2, Feb. 2020, pp. 173-8,
https://umj.imath.kiev.ua/index.php/umj/article/view/1106
.