Songsuwan, W., and N. Wattanasakulpong. “Amplitude analysis of functionally graded beams under linear decreasing and exponential loads”. Journal of Research and Applications in Mechanical Engineering 8, no. 1 (June 2, 2020): 1–10. accessed March 6, 2026. https://ph01.tci-thaijo.org/index.php/jrame/article/view/217970.