LE, Bui Hai; THUY, Tran Minh. Optimal design for eigen-frequencies of a longitudinal bar using Pontryagin’s maximum principle considering the influence of concentrated mass. <b>Vietnam Journal of Mechanics</b>, Hanoi, Vietnam, v. 39, n. 1, p. 1–12, 2017. DOI: 10.15625/0866-7136/6058. Disponível em: https://vjmech.vast.vn/vjmech/article/view/6058. Acesso em: 8 nov. 2025.