IVANOV , A. F.; MARUSHIYAK , P. On oscilation and asymptotic behaviour of solutions of one system of differential-functional equations of neutral type. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 44, n. 8, p. 1044–1049, 1992. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8032. Acesso em: 5 dec. 2025.