PELYUKH, G. P. On periodic solutions of difference equations with continuous argument. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 1, p. 140–145, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5374. Acesso em: 5 dec. 2025.