https://www.socialeurope.eu/lexit-fallacies
http://www.esf.be/new/wp-content/uploads/2018/07/ESF-Press-Release-on-Importance-of-Services-Trade-in-EU-UK-Future-Relastionship.pdf
https://www.nao.org.uk/wp-content/uploads/2017/07/The-Customs-Declaration-Service.pdf
https://onlinelibrary.wiley.com/doi/epdf/10.1111/jcms.13386