@book { GeschftsmodelleimElectronicCommerce,
    title = "Geschäftsmodelle im Electronic Commerce",
    author = "Manuel {Koubek}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832453237",
    url = "https://m.diplom.de/document/220887"
}