@Book{Biethahn.2004b,
  author = {Biethahn, Jörg and Mucksch, Harry and Ruf, Walter},
  title  = {Grundlagen},

  year   = {2004},
  number = {},
  url    = {},

  const  = {\ text}
}
@Book{Szyperski.2001,
  author = {Szyperski, Norbert},
  title  = {Unternehmungs-Informatik:  Grundlegende \"Uberlegungen zu einer Informationstechnologie f\"ur Unternehmungen},

  year   = {2001},
  number = {},
  url    = {},

  const  = {\ text}
}
@Book{Alpar.1998,
  author = {Alpar, Paul},
  title  = {Unternehmensorientierte Wirtschaftsinformatik:  Eine Einführung in die Strategie und Realisierung erfolgreicher IuK-Systeme},

  year   = {1998},
  number = {},
  url    = {},

  const  = {\ text}
}
@Book{Hummeltenberg.1998,
  author = {Hummeltenberg, Wilhelm},
  title  = {Information management for business and competitive intelligence and excellence:  Proceedings der Fr\"uhjahrstagung Wirtschaftsinformatik '98},

  year   = {1998},
  number = {},
  url    = {},

  const  = {\ text}
}