@book { SponsoringimdeutschenProfiFuball,
    title = "Sponsoring im deutschen Profi-Fußball",
    author = "Simon {Köster}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832471347",
    url = "https://m.diplom.de/document/222447"
}