GROVE, E. A.; LADAS, G. Periodicity in Nonlinear Difference Equations. CUBO, A Mathematical Journal, [S. l.], v. 4, n. 1, p. 192–227, 2002. Disponível em: https://cubo.ufro.cl/ojs/index.php/cubo/article/view/1731. Acesso em: 20 may. 2024.