https://infacts.org/fight-brexit-including-changing-mind/
http://docs.dpaq.de/10395-0216-euco-conclusions.pdf
http://www.migrationobservatory.ox.ac.uk/resources/reports/unsettled-status-which-eu-citizens-are-at-risk-of-failing-to-secure-their-rights-after-brexit/
http://www.strengthentheeuro.eu/fileadmin/files/user_upload/EZ_flashlight_europe_2017_05_ENG.pdf