KUMAR , S. . Natural Frequencies of Beams with Axial Material Gradation Resting on Two Parameter Elastic Foundation. Trends in Sciences, Nakhon Si Thammarat, Thailand, v. 19, n. 6, p. 3048, 2022. DOI: 10.48048/tis.2022.3048. Disponível em: https://tis.wu.ac.th/index.php/tis/article/view/3048. Acesso em: 8 apr. 2026.