@book{Pfeiffer1999,
  author    = {Pfeiffer, Johann},
  title     = {Verbesserung der Qualit{\"a}t von Freiformoberfl{\"a}chen},
  publisher = {Fachhochsch.},
  address   = {Aachen},
  year      = {1999},
  language  = {de}
}
@book{Pfeiffer1997,
  author    = {Pfeiffer, Johann},
  title     = {HSP III Koordinatenmessger{\"a}t},
  publisher = {Fachhochsch.},
  address   = {Aachen},
  year      = {1997},
  language  = {de}
}
@book{Pfeiffer1997,
  author    = {Pfeiffer, Johann},
  title     = {Design und Herstellen von Werkzeugen mit Freiformfl{\"a}chen},
  publisher = {Fachhochsch.},
  address   = {Aachen},
  year      = {1997},
  language  = {de}
}
@book{KnepperPfeiffer1995,
  author    = {Knepper, Ludger and Pfeiffer, Johann},
  title     = {Diplom-Ingenieur/Diplom-Ingenieurin (Fachhochschule) Maschinenbau - Allgemeiner Maschinenbau},
  publisher = {Bertelsmann},
  address   = {Bielefeld},
  pages     = {Loseblattausg.},
  year      = {1995},
  language  = {de}
}
@book{KnepperPfeiffer1998,
  author    = {Knepper, Ludger and Pfeiffer, Johann},
  title     = {Diplom-Ingenieur/Diplom-Ingenieurin (Fachhochschule) Maschinenbau Konstruktionstechnik},
  publisher = {Bertelsmann},
  address   = {Bielefeld},
  pages     = {Loseblattausg.},
  year      = {1998},
  language  = {de}
}
@book{KnepperPfeiffer1999,
  author    = {Knepper, Ludger and Pfeiffer, Johann},
  title     = {Diplom-Ingenieur / Diplom-Ingenieurin (Fachhochschule) Maschinenbau, Energie- und W{\"a}rmetechnik},
  publisher = {Bertelsmann},
  address   = {Bielefeld},
  pages     = {Loseblattausg.},
  year      = {1999},
  language  = {de}
}
@book{GauchelPfeiffer2003,
  author    = {Gauchel, Joachim and Pfeiffer, Johann},
  title     = {Kalibrierung Koordinatenmessger{\"a}t},
  address   = {FH Aachen},
  year      = {2003},
  language  = {de}
}