Sumida, M.; Takemoto, K.: 'Aberration of GRIN-rod lenses in single-mode optical devices', Electronics Letters, 1986, 22, (25), p. 1318-1319, DOI: 10.1049/el:19860904
IET Digital Library, https://digital-library.theiet.org/;jsessionid=52btd8t6nplpj.x-iet-live-01content/journals/10.1049/el_19860904