BISCONTI, L.; SPADINI, M. Harmonic perturbations with delay of periodic separated variables differential equations. Topological Methods in Nonlinear Analysis, [S. l.], v. 46, n. 1, p. 261–281, 2015. DOI: 10.12775/TMNA.2015.046. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2015.046. Acesso em: 3 jul. 2024.