@book { GemeinsameeuropischeAuenundSicherheitspolitik,
    title = "Gemeinsame europäische Außen- und Sicherheitspolitik ",
    author = "Ulrich {Rosengarten}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/b18543",
    url = "https://www.peterlang.com/document/1111709"
}