https://socialeurope.eu/brexit-why-does-northern-ireland-matter-so-much
http://www.reuters.com/article/us-britain-eu-verhofstadt-idUSKBN19V0WP
https://publications.parliament.uk/pa/ld5801/ldselect/ldeucom/248/248.pdf
https://www.bankofengland.co.uk/-/media/boe/files/report/2018/eu-withdrawal-scenarios-and-monetary-and-financial-stability.pdf?la=en&hash=B5F6EDCDF90DCC10286FC0BC599D94CAB8735DFB