@book { PolizeilicheZusammenarbeitinderEuropischenUnion,
    title = "Polizeiliche Zusammenarbeit in der Europäischen Union",
    author = "Gregor {Kämper}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1092411"
}