https://www.nao.org.uk/wp-content/uploads/2022/05/Regulating-after-EU-Exit.pdf
https://www.nscai.gov/wp-content/uploads/2021/03/Full-Report-Digital-1.pdf
https://ec.europa.eu/commission/sites/beta-political/files/aviation.pdf
https://ec.europa.eu/commission/sites/beta-political/files/customs_controls_0.pdf