
http://blogactiv.eu/blog/2012/05/15/stumbling-towards-the-brexit/

https://www.nao.org.uk/wp-content/uploads/2018/10/The-UK-border-preparedness-for-EU-exit.pdf

http://blogs.lse.ac.uk/brexit/2017/12/05/a-high-risk-game-of-chicken-is-being-played-over-the-irish-border/