
https://ec.europa.eu/commission/publications/position-paper-transmitted-eu27-goods-placed-market-under-union-law-withdrawal-date_en

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

https://www.publications.parliament.uk/pa/cm201617/cmselect/cmintrade/817/817.pdf