MEL'NIK, T. A. Linear singularly perturbed problems with pulse influence. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 1, p. 133–139, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4592. Acesso em: 5 dec. 2025.