
https://ukandeu.ac.uk/wp-content/uploads/2020/05/UKICE-Post-Brexit-Gov-NI-Report.pdf

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

https://www.europarl.europa.eu/doceo/document/B-9-2020-0098_EN.html?utm_source=POLITICO.EU&utm_campaign=3e49ba2509-EMAIL_CAMPAIGN_2020_02_13_05_53&utm_medium=email&utm_term=0_10959edeb5-3e49ba2509-190380769