Kandic, Miodrag; Bridges, Greg E.: 'Limits of passive and active negative group delay distributed circuits' (Materials, Circuits and Devices, 2018), 'Negative Group Delay Devices: From concepts to applications', Chap. 8, pp. 225-266, DOI: 10.1049/PBCS043E_ch8
IET Digital Library, https://digital-library.theiet.org/;jsessionid=4j72dovai82ok.x-iet-live-01content/books/10.1049/pbcs043e_ch8