http://www.resolutionfoundation.org/app/uploads/2017/10/Changing-Lanes-3.pdf
http://www.guengl.eu/uploads/publications-documents/NSkoutarisGUENGLReportC_%28002%29.pdf
https://ec.europa.eu/commission/sites/beta-political/files/joint_report.pdf
https://www.theguardian.com/politics/2017/nov/10/brexit-date-is-not-irreversible-says-man-who-wrote-article-50-lord-kerr