@book { WertpapierhandelimInternet,
    title = "Wertpapierhandel im Internet",
    author = "Oliver {Günther}",
    year = "1999",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832415266",
    url = "https://m.diplom.de/document/217371"
}