@book { Kundenorientierung,
    title = "Kundenorientierung",
    author = "Michaela {Kubillus}",
    year = "2004",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832483418",
    url = "https://m.diplom.de/document/223534"
}