@article{UBHD-68086806,
  author={Borchert, Bernd and Kuske, Dietrich and Stephan, Frank},
  title={On existentially first-order definable languages and their relation to NP},
  year={1999},
  pages={259-269},
  language={eng},
  issn={1290-385X},
  volume={33},
  number={3},
  note={Gesehen am 20.02.2017},
  journal={RAIRO},
  doi={10.1051/ita:1999116},
}