Rohokale, V. M. ., N. R. . Prasad, and R. . Prasad. “Cooperative Wireless Communications and Physical Layer Security: State-of-the-Art”. Journal of Cyber Security and Mobility, vol. 1, no. 2-3, Apr. 2012, pp. 226-49, doi:10.13052/jcsm2245-1439.1235.