BURSKII, V. P. On boundary-value problems for a second-order differential equation with complex coefficients in a plane domain. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 11, p. 1457–1467, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5199. Acesso em: 5 dec. 2025.