KIM, N.I.; HUYNH, T.A.; LIEU, Q.X.; LEE, J. NURBS-based optimization of natural frequencies for bidirectional functionally graded beams. Archives of Mechanics, Warsaw, Poland, v. 70, n. 4, p. 337–364, 2018. Disponível em: https://am.ippt.pan.pl/index.php/am/article/view/v70p337. Acesso em: 19 nov. 2025.