@book { ArbeiterklasseundStudiengebhren,
    title = "Arbeiterklasse und Studiengebühren",
    author = "Patrick H. M. {Maas}",
    year = "2005",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    url = "https://m.diplom.de/document/223912"
}