https://www.publications.parliament.uk/pa/cm201617/cmselect/cmbeis/909/909.pdf
http://fedtrust.co.uk/views-from-the-federal-trust/free-movement-and-migration/
https://ukandeu.ac.uk/wp-content/uploads/2020/05/UKICE-Post-Brexit-Gov-NI-Report.pdf
http://blogs.lse.ac.uk/brexit/2018/07/09/british-influence-in-brussels-had-been-far-greater-than-recognised/