@book { Kundenzufriedenheit,
    title = "Kundenzufriedenheit",
    author = "Hauke-Jan {Böttcher}",
    year = "1998",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832411626",
    url = "https://m.diplom.de/document/217085"
}