
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/cmworpen/848/848.pdf

http://carnegieeurope.eu/2017/06/15/bringing-brexit-back-to-reality-pub-71262