Ha, L. T., N. D. Kien, and V. T. Anh. “Dynamic Behavior of Nonuniform Functionally Graded Euler-Bernoulli Beams under Multiple Moving Forces”. Vietnam Journal of Mechanics, vol. 37, no. 3, Aug. 2015, pp. 151-68, doi:10.15625/0866-7136/37/3/4075.