Blake A. Troksa, Cam L. Key, Forest B. Kunkel, Slobodan V. Savić, Milan M. Ilić, and Branislav M. Notaroš. “Ray Tracing Using Shooting-Bouncing Technique to Model Mine Tunnels: Theory and Verification for a PEC Waveguide”. Applied Computational Electromagnetics Society Journal (ACES), vol. 34, no. 02, Feb. 2019, pp. 224-5, https://journals.riverpublishers.com/index.php/ACES/article/view/8607.