Preissig, R. S. ., and A. F. . Peterson. “A Rationale for P-Refinement With the Vector Helmholtz Equation and Two Dimensional Vector Finite Elements”. Applied Computational Electromagnetics Society Journal (ACES), vol. 19, no. 2, June 2022, pp. 65-75, https://journals.riverpublishers.com/index.php/ACES/article/view/16671.