Culshaw, B.: 'Independent control of temperature coefficient and breakdown voltage in Zener diodes', Electronics Letters, 1975, 11, (20), p. 499-500, DOI: 10.1049/el:19750385
IET Digital Library, https://digital-library.theiet.org/;jsessionid=bf7s6rhenk4qf.x-iet-live-01content/journals/10.1049/el_19750385