Javed, Y., A. S. Khan, A. Qahar, and J. Abdullah. “EEoP: A Lightweight Security Scheme over PKI in D2D Cellular Networks”. Journal of Telecommunication, Electronic and Computer Engineering (JTEC), vol. 9, no. 3-11, Dec. 2017, pp. 99-105, https://jtec.utem.edu.my/jtec/article/view/3191.