GÓRNIEWICZ, L.; NISTRI, P.; ZECCA, P. Control problems on closed subsets of ${\mathbb R}^n$ via feedback controls. Topological Methods in Nonlinear Analysis, [S. l.], v. 2, n. 1, p. 163–178, 1993. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1993.036. Acesso em: 25 apr. 2024.