@book { SportwetteninDeutschland,
    title = "Sportwetten in Deutschland",
    author = "Oliver {Koopmann}",
    year = "2008",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836610971",
    url = "https://m.diplom.de/document/225661"
}