RYBAKOWSKI, K. P. On proving existence and smoothness of invariant manifolds in singular perturbation problem. Topological Methods in Nonlinear Analysis, [S. l.], v. 2, n. 1, p. 21–34, 1993. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1993.028. Acesso em: 29 mar. 2024.