BOBOCHKO, V. N. Inner turning point in the theory of singular Perturbations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 7, p. 876–890, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5260. Acesso em: 5 dec. 2025.