@book { OnlineWerbung,
    title = "Online-Werbung",
    author = "Heiko {Walz}",
    year = "2000",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832429348",
    url = "https://m.diplom.de/document/218658"
}