https://openeurope.org.uk/today/blog/what-would-a-no-deal-after-the-transition-period-look-like/
http://www.cer.eu/sites/default/files/bulletin_118_js-sl_article2.pdf
https://trade.ec.europa.eu/doclib/docs/2018/april/tradoc_156791.pdf
https://institute.global/news/customs-and-exiting-european-union