Kovtonyuk, D. A., I. V. Petkov, and V. I. Ryazanov. “On the Dirichlet Problem for the Beltrami Equations in Finitely Connected Domains”. Ukrains’kyi Matematychnyi Zhurnal 64, no. 7 (July 25, 2012): 932–944. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/2629.