L. Tran Hoang, H. Nguyen Huy, A. Phan Huy, T. Truong Xuan, T. Nguyen Thi Thu, and H. Nguyen Thanh, “Optimizing beamforming power in multi-antenna transmission with eavesdroppers”, J. Mil. Sci. Technol., no. CBNCT, pp. 30–39, Nov. 2021.