LIU, Y.; LIU, X. Three Positive Periodic Solutions of Nonlinear Functional Difference Equations. Sarajevo Journal of Mathematics, [S. l.], v. 4, n. 2, p. 215–231, 2024. DOI: 10.5644/SJM.04.2.07. Disponível em: https://sjm.anubih.ba/index.php/sjm/article/view/365. Acesso em: 15 oct. 2024.