M.M. Ameen, S., and A. A. Amara. “Computation of Propagation Characteristics in Complex Plane for Multilayer Optical Waveguide”. University of Thi-Qar Journal of Science, Vol. 1, no. 4, May 2019, pp. 118-33, https://www.jsci.utq.edu.iq/index.php/main/article/view/211.