@book { DerSmartShopper,
    title = "Der Smart Shopper",
    author = "Michael {Pusch}",
    year = "1998",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832406035",
    url = "https://m.diplom.de/document/216536"
}