@Book{ls_leimeister,
  author = {Shubik, Martin},
  title  = {Spieltheorie und Sozialwissenschaften},

  year   = {1964},
  number = {},
  url    = {},

  const  = {\ text}
}
@Book{Friedrichs.,
  author = {Friedrichs, Jürgen},
  title  = {Methoden empirischer Sozialforschung},

  year   = {-},
  number = {},
  url    = {},

  const  = {\ text}
}
@Book{Lisch.,
  author = {Lisch, Ralf and Kriz, Jürgen},
  title  = {Grundlagen der Modelle der Inhaltsanalyse},

  year   = {-},
  number = {},
  url    = {},

  const  = {\ text}
}