https://ec.europa.eu/commission/sites/beta-political/files/customs_controls_0.pdf
https://ecipe.org/wp-content/uploads/2023/06/ECI_23_PolicyBrief_06-2023_LY05.pdf
https://www.fraserinstitute.org/sites/default/files/economic-freedom-of-the-world-2021.pdf
https://www.irishtimes.com/opinion/editorial/the-irish-times-view-on-brexit-day-britain-s-great-leap-backwards-1.4156666