Thabit, Samar A., Khalid A. Hadi, and Loay E. George. “Determination of the Annual Optimal Reliable Frequency for Different Transmitter/Receiver Stations Distributed over the Iraqi Territory”. Iraqi Journal of Science 62, no. 4 (April 30, 2021): 1386-1395. Accessed December 6, 2021. https://ijs.uobaghdad.edu.iq/index.php/eijs/article/view/2725.