@book { VertriebdigitalerMusikimInternet,
    title = "Vertrieb digitaler Musik im Internet",
    author = "",
    year = "2008",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638019187",
    url = "https://www.hausarbeiten.de/document/88218"
}