On local asymptotic expansions of singularly perturbed systems of differential equations with a degeneration in a point. Neliniini Kolyvannya, [S. l.], v. 12, n. 2, p. 279–285, 2009. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/525. Acesso em: 21 jan. 2026.