@book { DerdigitaleMusikmarkt,
    title = "Der digitale Musikmarkt",
    author = "Takis {Kouretsidis}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836603775",
    url = "https://m.diplom.de/document/228916"
}