http://ec.europa.eu/eurostat/statistics-explained/index.php/Acquisition_of_citizenship_statistics
https://www.socialeurope.eu/deja-vu-home-office
http://cadmus.eui.eu/bitstream/handle/1814/45187/Ebook_IntegrationMigrantsRefugees2017.pdf?sequence=3&isAllowed=y
http://www.migrationobservatory.ox.ac.uk/resources/commentaries/brexodus-migration-and-uncertainty-after-the-eu-referendum/