https://socialeurope.eu/brexit-why-does-northern-ireland-matter-so-much
http://www.icaew.com/-/media/corporate/files/technical/economy/brexit/eu-exit-charge.ashx
http://www.lawyersforbritain.org/eu-deal-financial-liabilities.shtml
https://ukandeu.ac.uk/the-future-of-the-uk-eu-relationship/?mc_cid=f8b68a972a&mc_eid=815b1928ec