AKEL, M. S. M.; BEGEHR, H. Schwarz problem for first order elliptic systems in unbounded sectors. Eurasian Mathematical Journal, [S. l.], v. 5, n. 4, p. 6–24, 2014. Disponível em: https://emj.enu.kz/index.php/main/article/view/585. Acesso em: 18 sep. 2025.