Georgios G. Pyrialakos, Theodoros T. Zygiridis, and Nikolaos V. Kantartzis. “A 3-D Polynomial-Chaos FDTD Technique for Complex Inhomogeneous Media With Arbitrary Stochastically-Varying Index Gradients”. Applied Computational Electromagnetics Society Journal (ACES), vol. 33, no. 02, July 2021, pp. 144-7, https://journals.riverpublishers.com/index.php/ACES/article/view/9253.