@book { GeschftsmodellefrdasEBusiness,
    title = "Geschäftsmodelle für das E-Business",
    author = "Bernhard {Kerschbaum}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832456795",
    url = "https://m.diplom.de/document/221157"
}