@book { Kundenzufriedenheit,
    title = "Kundenzufriedenheit",
    subtitle = "Ein Erfolgsfaktor unternehmerischen Handelns",
    author = "Anke {Kolbe}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832472610",
    url = "https://m.diplom.de/document/222562"
}