Anh LTN, Ninh VTA, Lang TV, Kien ND. Free vibration of bidirectional functionally graded sandwich beams using a first-order shear deformation finite element formulation. JSTCE [Internet]. 2020Aug.19 [cited 2026Sep.18];14(3):136-50. Available from: https://stce.vjst.net/index.php/en/article/view/1746