http://www.cer.eu/sites/default/files/pb_ireland_brexit_6.7.17.pdf
https://www.sussex.ac.uk/webteam/gateway/file.php?name=briefing-paper-1.pdf&site=18
https://www.rand.org/pubs/research_reports/RR2200.html
https://blogs.lse.ac.uk/brexit/2021/02/04/indyref2-scottish-independence-would-be-2-3-times-more-costly-than-that-of-brexit-and-rejoining-the-eu-wouldnt-make-up-the-difference/