@book { DieStaatlichkeitvonBeihilfen,
    title = "Die Staatlichkeit von Beihilfen",
    author = "Rüdiger {Schmid-Kühnhöfer}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1098240"
}