@book { ProfifuballvereinealsMarke,
    title = "Profifußballvereine als Marke",
    author = "Till {Eckel}",
    year = "2006",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832492151",
    url = "https://m.diplom.de/document/224338"
}