BORSUK, M. V. On the solvability of the dirichlet problem for elliptic nondivergent equations of the second order in a domain with conical point. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 1, p. 13–24, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5358. Acesso em: 5 dec. 2025.