@book{StrassnerNeuendorff2011,
  author    = {Strassner, C and Neuendorff, J.},
  title     = {Mit einfachen Schritten zur Bio-Zertifizierung. Der neue Leitfaden f{\"u}r Gemeinschaftsverpflegung und Gastronomie},
  editor    = {Roehl, R},
  edition   = {4. vollst{\"a}ndig {\"u}bera},
  address   = {M{\"u}nster},
  isbn      = {978-3-9813008-2-6},
  pages     = {28 S.},
  year      = {2011},
  language  = {de}
}
@book{StrassnerNeuendorff2011,
  author    = {Strassner, C and Neuendorff, J.},
  title     = {Easy Steps To Organic Certification. The updated manual for canteens, restaurants and foodservice operators.},
  editor    = {Roehl, R.},
  edition   = {2. vollst{\"a}ndig {\"u}bera},
  address   = {M{\"u}nster},
  isbn      = {978-3-9813008-1-9},
  pages     = {28 S.},
  year      = {2011},
  language  = {en}
}
@book{PreiserBrusdeylins2011,
  author    = {Preiser, Siegfried and Brusdeylins, Kerstin},
  title     = {Psychologiedidaktik und Evaluation VIII},
  editor    = {Kr{\"a}mer, Michael},
  edition   = {1. Aufl},
  publisher = {Shaker},
  address   = {Aachen},
  isbn      = {978-3-8440-0006-1},
  pages     = {399 S},
  year      = {2011},
  language  = {de}
}