Sung, Wonjin: 'Minimum decoding trellis lengths for tail-biting convolutional codes', Electronics Letters, 2000, 36, (7), p. 643-645, DOI: 10.1049/el:20000517
IET Digital Library, https://digital-library.theiet.org/;jsessionid=1dqffhuwf6uhh.x-iet-live-01content/journals/10.1049/el_20000517