http://blogactiv.eu/blog/2012/05/15/stumbling-towards-the-brexit/
http://www.res.org.uk/view/art4Apr17Features.html
https://publications.parliament.uk/pa/cm201719/cmselect/cmcumeds/365/365.pdf
https://www.instituteforgovernment.org.uk/sites/default/files/publications/5704%20IFG%20-%20Frictionless%20Trade%20Web.pdf