https://www.theguardian.com/politics/2017/sep/04/uk-trade-deals-after-brexit-theresa-may-eu
http://www.nfuonline.com/assets/96747
https://economiesuisse.ch/de/print/pdf/node/49145
https://theconversation.com/why-the-eus-singapore-ruling-does-not-lead-to-a-smoother-brexit-road-for-britain-78116