@article{HornKoutzevlovRaetschetal.1996,
  author    = {Horn, Erika and Koutzevlov, Atanas and R{\"a}tsch, Gunnar and Schubert, Wolfgang and Tschapek, Alexej},
  title     = {Software system specification},
  series = {HGG-Dokument},
  volume    = {UPHGG.010.4},
  journal   = {HGG-Dokument},
  publisher = {Univ.},
  address   = {Potsdam},
  year      = {1996},
  language  = {en}
}
@article{HornNeuhausRaetschetal.1996,
  author    = {Horn, Erika and Neuhaus, Alexander and R{\"a}tsch, Gunnar and Schubert, Wolfgang and Tschapek, Alexej},
  title     = {Software development plan},
  series = {HGG-Dokument},
  volume    = {UPHGG.002.4},
  journal   = {HGG-Dokument},
  publisher = {Univ.},
  address   = {Potsdam},
  year      = {1996},
  language  = {en}
}