@book { DerHandelmitvirtuellenGtern,
    title = "Der Handel mit virtuellen Gütern",
    author = "Stefan {Heinz}",
    year = "2010",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783842807549",
    url = "https://m.diplom.de/document/228173"
}