@book { WettbewerbsbeschrnkungeninprofessionellenSportligen,
    title = "Wettbewerbsbeschränkungen in professionellen Sportligen",
    author = "Mario {Konrad}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    url = "https://m.diplom.de/document/225442"
}