@article{Staudacher1994,
  author    = {Staudacher, Peter},
  title     = {Neue Grenzen jenseits der Kontextfreiheit},
  year      = {1994},
  language  = {de}
}
@article{Staudacher1993,
  author    = {Staudacher, Peter},
  title     = {New frontiers beyond context-freeness},
  isbn      = {90-5434-014-2},
  year      = {1993},
  language  = {en}
}