https://www.publications.parliament.uk/pa/ld201617/ldselect/ldeucom/169/169.pdf
https://www.gov.uk/government/news/david-davis-opening-remarks-at-the-start-of-the-third-round-of-eu-exit-negotiations
http://bruegel.org/wp-content/uploads/2017/03/WP_2017_03-.pdf
http://www.cer.eu/sites/default/files/pb_ireland_brexit_6.7.17.pdf