https://cer.org.uk/sites/default/files/bulletin_114_js_st_article1.pdf
http://blogs.lse.ac.uk/brexit/2017/07/06/the-1bn-bung-wont-protect-northern-ireland-from-the-pain-of-a-hard-brexit/
https://ec.europa.eu/commission/publications/position-paper-essential-principles-citizens-rights_en
https://ec.europa.eu/commission/sites/beta-political/files/revised_withdrawal_agreement_including_protocol_on_ireland_and_nothern_ireland.pdf