@book { ErtragsbesteuerungderInternetprovider,
    title = "Ertragsbesteuerung der Internetprovider",
    author = "Jörg Thomas {Knies}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1095708"
}