Ameen, Siddeeq Y., Abbas A. Al-Shalchi, and Muhanad D. Al-Bayati. 2008. “Design and Hardware Implementation of a Speech Cipher System”. Nahrain University College of Engineering Journal 10 (1): 1-10. https://oldjournal.eng.nahrainuniv.edu.iq/index.php/main/article/view/528.