https://www.eca.europa.eu/Lists/ECADocuments/REW19_09/REW_EU-defence_EN.pdf
https://www.greatbritishpolitics.co.uk/europe/654-dual-nationality-and-the-hurdles-facing-britons-who-want-to-keep-eu-citizenship-after-brexit.html
https://unctad.org/system/files/official-document/diaeiainf2021d1_en.pdf