NIU, Y.; YAN, B. The existence of positive solutions for the singular two-point boundary value problem. Topological Methods in Nonlinear Analysis, [S. l.], v. 49, n. 2, p. 665–682, 2017. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2017.004. Acesso em: 4 feb. 2023.