DANCER, E. Norman; WEI, Juncheng. On the effect of domain topology in a singular perturbation problem. Topological Methods in Nonlinear Analysis, [S. l.], v. 11, n. 2, p. 227–248, 1998. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1998.016. Acesso em: 8 jul. 2025.