@book { DatabaseMarketingimVersandhandelinDeutschland,
    title = "Database Marketing im Versandhandel in Deutschland",
    author = "Frank {Armbrust}",
    year = "1997",
    publisher = "Diplom.de",
    address = "Hamburg, Germany",
    doi = "10.3239/9783832402549",
    url = "https://m.diplom.de/document/216199"
}