DERFEL', G. A.; ROMANENKO, Ye. Yu.; SHARKOVSKY, O. M. Asymptotic Discontinuity of Smooth Solutions of Nonlinear $q$-Difference Equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 52, n. 12, p. 1615–1629, 2000. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4566. Acesso em: 5 dec. 2025.