MITROPOLSKY, Y. A.; Fоdchuk V. I. Asymptotic methods of nonlinear mechanics as applied to nonlinear differential equations with delayed argument. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 18, n. 3, p. 65–84, 1966. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8738. Acesso em: 5 dec. 2025.