Kefeng Guo, Kang An, Feng Zhou, Theodoros A. Tsiftsis, Gan Zheng, Symeon Chatzinotas: On the Secrecy Performance of NOMA-Based Integrated Satellite Multiple-Terrestrial Relay Networks With Hardware Impairments. IEEE Trans. Veh. Technol. 70(4): 3661-3676 (2021)