https://blogs.lse.ac.uk/brexit/2019/10/09/northern-ireland-depends-on-the-eus-fluid-borders-for-survival/
https://ecipe.org/wp-content/uploads/2024/04/ECI_24_PolicyBrief_08-2024_LY05.pdf
https://www.dw.com/en/brexit-german-leaders-write-emotional-letter-to-britain/a-47132376