https://www.socialeurope.eu/trump-and-brexit
https://publications.parliament.uk/pa/cm201719/cmselect/cmbeis/379/379.pdf
http://fedtrust.co.uk/views-from-the-federal-trust/free-movement-and-migration/
http://foodresearch.org.uk/wp-content/uploads/2016/03/Food-and-Brexit-briefing-paper-2.pdf