@article{KolbMichaelisMoennichetal.2003,
  author    = {Kolb, Hans-Peter and Michaelis, Jens and M{\"o}nnich, Uwe and Morawietz, Frank},
  title     = {An operational and denotational approach to non-context-freeness},
  issn      = {0304-3975},
  year      = {2003},
  language  = {en}
}