Townsend, G.B.: 'Colour-television-system parameters', Electronics Letters, 1965, 1, (1), p. 11-12, DOI: 10.1049/el:19650011
IET Digital Library, https://digital-library.theiet.org/;jsessionid=1968ho7mqn7q.x-iet-live-01content/journals/10.1049/el_19650011