Periodic solutions of a system of integro-differential equations with an impulsive effect. Neliniini Kolyvannya, [S. l.], v. 8, n. 4, p. 553–573, 2005. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/373. Acesso em: 22 jan. 2026.