@book{HufnagelRueth2007,
  author    = {Hufnagel, W. and R{\"u}th, D.},
  title     = {Internes Rechnungswesen, LE 1-5},
  address   = {Hagen},
  year      = {2007},
  language  = {mul}
}
@book{HufnagelTeutemacher2007,
  author    = {Hufnagel, W. and Teutemacher, T.},
  title     = {Betriebliches Rechnungswesen, Externes Rechnungswesen, LE 1-4},
  address   = {Hagen},
  year      = {2007},
  language  = {mul}
}
@book{Hufnagel2009,
  author    = {Hufnagel, W.},
  title     = {Managementsysteme, LE1},
  address   = {Hagen},
  year      = {2009},
  language  = {mul}
}
@book{HufnagelHoldt2002,
  author    = {Hufnagel, W. and Holdt, W.},
  title     = {Betriebliches Rechnungswesen, Externes Rechnungswesen LE 1-4},
  address   = {Hagen},
  year      = {2002},
  language  = {mul}
}
@book{HufnagelTeutemacher2004,
  author    = {Hufnagel, W. and Teutemacher, T.},
  title     = {Externes Rechnungswesen, LE 1-4},
  address   = {Hagen},
  year      = {2004},
  language  = {mul}
}
@book{Hufnagel2010,
  author    = {Hufnagel, W.},
  title     = {Managementsysteme, LE 1},
  address   = {Hagen},
  year      = {2010},
  language  = {mul}
}
@book{HufnagelKuehn2009,
  author    = {Hufnagel, W. and K{\"u}hn, R.},
  title     = {Betriebliches Rechnungswesen, Externes Rechnungswesen, LE 1-4},
  address   = {Hagen},
  year      = {2009},
  language  = {mul}
}
@book{HufnagelRueth2010,
  author    = {Hufnagel, W. and R{\"u}th, D.},
  title     = {Internes Rechnungswesen, LE 1-5},
  address   = {Hagen},
  year      = {2010},
  language  = {mul}
}
@book{Hufnagel2011,
  author    = {Hufnagel, W.},
  title     = {Management unterst{\"u}tztes Controlling, LE1 - LE 4},
  address   = {M{\"u}nster},
  year      = {2011},
  language  = {mul}
}
@misc{Ziegenbein2016,
  author    = {Ziegenbein, R.},
  title     = {\#KMU - Herausforderung digitale Transformation, FI-Forum 2016 am 16. November 2016 in Frankfurt am Main},
  year      = {2016},
  language  = {mul}
}