@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}
}