KULIK, V. L.; KULYK, H. M. Integral Form of Bounded Solutions of Some Systems of Differential Equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 57, n. 1, p. 84–93, 2005. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3575. Acesso em: 5 dec. 2025.