http://www.assemblee-nationale.fr/14/pdf/rap-info/i4551.pdf
https://s3.eu-central-1.amazonaws.com/euobs-media/59f9f4116a089cec71bf81b76413503a.pdf
https://www.opendemocracy.net/uk/looking-at-lexit/guy-aitchison/borders-open-borders-or-no-borders?utm_source=Daily+Newsletter&utm_campaign=0a51e05bcc-DAILY_NEWSLETTER_MAILCHIMP&utm_medium=email&utm_term=0_717bc5d86d-0a51e05bcc-407405485
https://carnegieendowment.org/politika/88202