http://ec.europa.eu/eurostat/statistics-explained/index.php/Acquisition_of_citizenship_statistics
http://www.migrationobservatory.ox.ac.uk/resources/reports/unsettled-status-which-eu-citizens-are-at-risk-of-failing-to-secure-their-rights-after-brexit/
https://www.politico.eu/article/france-america-charles-michel-armenia-azerbaijan-nagorno-karabakh-refugees/
http://www.resolutionfoundation.org/app/uploads/2018/02/IC-international.pdf