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

https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32019R0452&from=EN

https://cdn.ymaws.com/www.export.org.uk/resource/resmgr/docs/policy_papers/IOE&IT_report_with_EY_TradeT.pdf