Sze, K. Y., W. G. Jin, N. Sheng, and J. Li. “Trefftz Methods for Plane Piezoelectricity”. Computer Assisted Methods in Engineering and Science 10, no. 4 (January 26, 2023): 619–627. Accessed April 19, 2025. https://cames3.ippt.pan.pl/index.php/cames/article/view/1070.