https://bdi.eu/#/artikel/news/europa-muss-ein-worst-case-szenario-verhindern/
http://bruegel.org/wp-content/uploads/2017/03/WP_2017_03-.pdf
https://theconversation.com/why-the-eus-singapore-ruling-does-not-lead-to-a-smoother-brexit-road-for-britain-78116
http://www.reuters.com/article/us-britain-eu-verhofstadt-idUSKBN19V0WP