
http://www.guengl.eu/uploads/news-documents/Working_paper_Border_controls_on_cross_border_trade_in_goods.pdf

http://www.guengl.eu/news/article/eu-citizens-rights-and-status-of-north-of-ireland-must-be-prioritised-in-br

https://www.theguardian.com/politics/2017/nov/10/brexit-date-is-not-irreversible-says-man-who-wrote-article-50-lord-kerr