@book { PourquoilUnionEuropenne,
    title = "Pourquoi l’Union Européenne?",
    author = "Nataliya {Gudz}",
    year = "2008",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640184224",
    url = "https://www.hausarbeiten.de/document/116374"
}