1.
Dang DC, Vu T. Asymptotic Equivalence of Triangular Differential Equations in Hilbert Spaces. Ukr. Mat. Zhurn. [Internet]. 2005 Mar. 25 [cited 2025 Apr. 24];57(3):329–337. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/3601