M. Ahmad and D. Kasilingam, “Three-Dimensional Modeling of Wave Propagation over Different Types of Terrains and Environments Using the Parabolic Equation Solved by Higher Order Approximation of the Finite Difference Method”, IJEEI, vol. 9, no. 2, pp. 417–425, May 2021, doi: 10.52549/ijeei.v9i2.2845.