https://ec.europa.eu/commission/sites/beta-political/files/customs_controls_0.pdf
https://unherd.com/2021/12/what-hope-for-the-united-kingdom/
https://docs.wto.org/dol2fe/Pages/SS/directdoc.aspx?filename=q:/INF/TESSD/R4.pdf&Open=True
https://ecipe.org/wp-content/uploads/2020/08/ECI_20_PolicyBrief_06_2020_LY06.pdf