Ke, H. ., and T. H. . Hubing. “Low-Frequency Full-Wave Finite Element Modeling Using the LU Recombination Method”. Applied Computational Electromagnetics Society Journal (ACES), vol. 23, no. 4, June 2022, pp. 303-8, https://journals.riverpublishers.com/index.php/ACES/article/view/16095.