J. A. Teixeira de Freitas, “Hybrid-Thefftz displacement and stress elements for elastodynamic analysis in the frequency domain”, Comp. Assist. Methods Eng. Sci., vol. 4, no. 3-4, pp. 345–368, Jun. 2023, Accessed: Jun. 29, 2025. [Online]. Available: https://cames.ippt.pan.pl/index.php/cames/article/view/1378