@book { KundenzufriedenheitsanalysefrdieFirmaXXX,
    title = "Kundenzufriedenheitsanalyse für die Firma XXX",
    author = "Ricky {Kohl}",
    year = "1998",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832411947",
    url = "https://m.diplom.de/document/217114"
}