Kovtonyuk, D. A., I. V. Petkov, and V. I. Ryazanov. “On the Boundary Behavior of Solutions of the Beltrami Equations”. Ukrains’kyi Matematychnyi Zhurnal 63, no. 8 (August 25, 2011): 1078-1091. Accessed January 18, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/2786.