
https://ec.europa.eu/commission/sites/beta-political/files/customs_controls_0.pdf

https://ukandeu.ac.uk/wp-content/uploads/2021/02/UK-regulation-after-Brexit.pdf?mc_cid=1d4cf56e72&mc_eid=815b1928ec

https://bdi.eu/media/user_upload/20171005_Pressemitteilung_Brexit.pdf