Borsuk , M. V. “Behaviour of Solutions of the Dirichlet Problem for Quasilinear Elliptical Equations of the Second Order of a General Kind Near Angular Point”.
Ukrains’kyi Matematychnyi Zhurnal 44, no. 2 (February 28, 1992): 167–173. Accessed April 7, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/7828.