http://www.guengl.eu/uploads/publications-documents/NSkoutarisGUENGLReportC_%28002%29.pdf
https://sp-bpr-en-prod-cdnep.azureedge.net/published/2018/2/2/Common-UK-Frameworks-after-Brexit/SB%2018-09.pdf
https://ec.europa.eu/commission/publications/terms-reference-article-50-treaty-european-union-negotiations_en
https://publications.parliament.uk/pa/cm201719/cmselect/cmexeu/935/935.pdf