
https://policyexchange.org.uk/wp-content/uploads/2017/06/Defying-Gravity-A-critique-of-estimates-of-the-economic-impact-of-Brexit.pdf

https://publications.parliament.uk/pa/cm201719/cmselect/cmbeis/379/379.pdf

https://ec.europa.eu/commission/sites/beta-political/files/guiding-principles-dialogue-ei-ni_en.pdf