http://publications.iom.int/system/files/pdf/wmr_2018_en.pdf
https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:52024DC0075
http://blogs.lse.ac.uk/brexit/2018/05/15/switzerland-wanted-more-immigration-controls-but-economic-self-interest-will-probably-prevail/
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