https://blogs.lse.ac.uk/brexit/2019/04/15/brexit-lessons-from-the-silesian-backstop-of-1919-25/
https://publications.parliament.uk/pa/cm201719/cmselect/cmintrade/520/520.pdf
http://ukandeu.ac.uk/brexit-a-french-perspective/
https://socialeurope.eu/brexit-why-does-northern-ireland-matter-so-much