Biao He, ; Lau, Vincent K.; Xiangyun Zhou, ; Swindlehurst, A. Lee: 'Secrecy metrics for physical layer security over fading channels' (Telecommunications, 2017), 'Trusted Communications with Physical Layer Security for 5G and Beyond', Chap. 1, pp. 3-19, DOI: 10.1049/PBTE076E_ch1
IET Digital Library, https://digital-library.theiet.org/;jsessionid=tavmhr3bp6ty.x-iet-live-01content/books/10.1049/pbte076e_ch1