@book { QualittsmanagementimProduktbereich,
    title = "Qualitätsmanagement im Produktbereich",
    author = "Olaf {Unger}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832437398",
    url = "https://m.diplom.de/document/219423"
}