
https://blogs.lse.ac.uk/brexit/2019/10/09/northern-ireland-depends-on-the-eus-fluid-borders-for-survival/

https://ukandeu.ac.uk/explainers/the-protocol-on-ireland-northern-ireland/?mc_cid=2bd4dc8e93&mc_eid=815b1928ec

https://www.nakedcapitalism.com/2018/02/another-brexit-mess-grandfathering-existing-free-trade-agreements-looks-unlikely.html