https://www.gov.uk/government/news/david-davis-speech-to-the-suddeutsche-zeitung-economic-summit
http://www.res.org.uk/view/art4Apr17Features.html
https://publications.parliament.uk/pa/ld201719/ldselect/ldeucom/129/129.pdf
https://www.bloomberg.com/news/articles/2017-06-14/ryanair-easyjet-say-soft-brexit-won-t-address-airline-concerns?cmpid=BBBXT061517_BIZ&utm_medium=email&utm_source=newsletter&utm_term=170615&utm_campaign=brexit