@book{GauchelPfeiffer2003,
  author    = {Gauchel, Joachim and Pfeiffer, Johann},
  title     = {Kalibrierung Koordinatenmessger{\"a}t},
  address   = {FH Aachen},
  year      = {2003},
  language  = {de}
}
@book{Pfeiffer2003,
  author    = {Pfeiffer, Johann},
  title     = {3D-Freiformfl{\"a}chenmessung},
  publisher = {Fachhochsch.},
  address   = {Aachen},
  year      = {2003},
  language  = {de}
}