Linear Elliptic Systems with Nonlinear Boundary Conditions without Landesman-Lazer Conditions. Global Journal of Science Frontier Research, [S. l.], v. 15, n. F3, p. 9–15, 2015. Disponível em: https://www.journalofscience.org/index.php/GJSFR/article/view/1540. Acesso em: 14 aug. 2026.