MALLET-PARET, John; NUSSBAUM, Roger D.; PARASKEVOPOULOS, Panagiotis. Periodic solutions for functional differential equations with multiple state-depend time lags. Topological Methods in Nonlinear Analysis, [S. l.], v. 3, n. 1, p. 101–162, 1994. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1994.006. Acesso em: 1 jul. 2025.