Koh, J.-S.; Kim, J.-K.: 'Simple block-effect reduction method for image coding with vector quantisation', Electronics Letters, 1987, 23, (14), p. 713-714, DOI: 10.1049/el:19870506
IET Digital Library, https://digital-library.theiet.org/;jsessionid=1cmnx74yqhmgf.x-iet-live-01content/journals/10.1049/el_19870506