@article{BordihnMitrana2020,
  author    = {Henning Bordihn and Victor Mitrana},
  title     = {On the degrees of non-regularity and non-context-freeness},
  journal   = {Journal of computer and system sciences},
  volume    = {108},
  pages     = {104 -- 117},
  doi       = {10.1016/j.jcss.2019.09.003},
  year      = {2020},
}