O’REGAN, D. Singular nonlinear differential equations on the half line. Topological Methods in Nonlinear Analysis, [S. l.], v. 8, n. 1, p. 137–159, 1996. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1996.024. Acesso em: 22 jul. 2024.