DANG, Dinh Chau; VU, Tuan. Asymptotic Equivalence of Triangular Differential Equations in Hilbert Spaces. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 57, n. 3, p. 329–337, 2005. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3601. Acesso em: 27 apr. 2025.