@book { DerMarktfrGratiszeitungeninsterreich,
    title = "Der Markt für Gratiszeitungen in Österreich",
    author = "Thomas {Driendl}",
    year = "2005",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832440763",
    url = "https://m.diplom.de/document/219705"
}