@book { EBusinessimInternet,
    title = "E-Business im Internet",
    author = "Ferhat {Ünlü}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832457068",
    url = "https://m.diplom.de/document/221178"
}