MEL'NIK, T. A. Asymptotics of solutions of discontinuous singularly perturbed boundary-value problems. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 6, p. 861–864, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4675. Acesso em: 5 dec. 2025.