Lifits, Sergei, Sergei Reutskiy, and Brunello Tirozzi. “Trefftz Spectral Method for Initial-Boundary Problems”. Computer Assisted Methods in Engineering and Science 4, no. 3-4 (December 31, 1997): 549–565. Accessed March 5, 2026. https://cames.ippt.gov.pl/index.php/cames/article/view/1389.