https://www.gov.uk/guidance/status-of-eu-nationals-in-the-uk-what-you-need-to-know
http://ukandeu.ac.uk/wp-content/uploads/2018/10/The-mechanics-of-a-further-referendum-on-Brexit-Constitution-Unit-Report-1.pdf
https://www.nakedcapitalism.com/2018/02/another-brexit-mess-grandfathering-existing-free-trade-agreements-looks-unlikely.html
http://europa.eu/rapid/press-release_MEMO-17-2001_en.htm