http://fedtrust.co.uk/views-from-the-federal-trust/free-movement-and-migration/
https://www.niesr.ac.uk/sites/default/files/UK%20Economy%20Press%20Release%20-NIER%20No245%20%20August%202018%20-%20EMBARGOED%20until%2000.01%20Wednesday%201st%20August.pdf
https://sp-bpr-en-prod-cdnep.azureedge.net/published/2018/2/2/Common-UK-Frameworks-after-Brexit/SB%2018-09.pdf