New results on periodic solutions for a nonlinear fourth-order iterative differential equation. Journal of Prime Research in Mathematics, [S. l.], v. 18, n. 2, p. 88 – 99, 2022. Disponível em: https://jprm.sms.edu.pk/index.php/jprm/article/view/199. Acesso em: 11 apr. 2026.