WONG, P. J. Y.; AGARWAL, R. P. On the existence of positive solutions of higher order difference equations. Topological Methods in Nonlinear Analysis, [S. l.], v. 10, n. 2, p. 339–351, 1997. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1997.036. Acesso em: 22 jul. 2024.