Ihlenburg, Frank, and Ivo Babuška. “Solution of Helmholtz Problems by Knowledge-Based FEM”. Computer Assisted Methods in Engineering and Science 4, no. 3-4 (June 19, 2023): 397–415. Accessed January 12, 2025. https://cames3.ippt.pan.pl/index.php/cames/article/view/1381.