AMSTER, P.; EPSTEIN, J.; SANJUÁN CUÉLLAR, A. Periodic solutions for systems of functional-differential semilinear equations at resonance. Topological Methods in Nonlinear Analysis, [S. l.], v. 58, n. 2, p. 591–607, 2021. DOI: 10.12775/TMNA.2020.078. Disponível em: https://apcz.umk.pl/TMNA/article/view/36413. Acesso em: 3 jul. 2024.