https://www.ajot.com/news/the-brexit-checklist-where-the-u.k.-and-eu-currently-stand
http://uk.reuters.com/article/us-britain-eu-negotiations-idUKKBN17R1XJ
https://publications.parliament.uk/pa/cm201719/cmselect/cmhaff/961/961.pdf
https://www.ips-journal.eu/interviews/theres-a-broad-consensus-in-denmark-around-migration-7635/