SI, N. T. On modal analysis of mechanical systems. Vietnam Journal of Mechanics, Hanoi, Vietnam, v. 10, n. 2, p. 21–24, 1988. DOI: 10.15625/0866-7136/10326. Disponível em: https://vjs.ac.vn/index.php/vjmech/article/view/10326. Acesso em: 26 apr. 2024.