Conditions for existence of almost periodic solutions of nonlinear difference equations with discrete argument. Neliniini Kolyvannya, [S. l.], v. 16, n. 3, p. 416–425, 2013. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/709. Acesso em: 8 dec. 2025.