
https://institute.global/sites/default/files/2020-07/Tony%20Blair%20Institute%2C%20A%20Path%20to%20Brexit%20Agreement%2C%20July%202020.pdf

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

https://lawliberty.org/forum/free-trades-origin-myth/