http://www.bakermckenzie.com/-/media/files/insight/publications/brexit_tradeflows.pdf?la=en
http://www.acea.be/uploads/publications/ACEA_position_paper-Brexit.pdf
https://www.nao.org.uk/wp-content/uploads/2017/07/The-Customs-Declaration-Service.pdf
https://ukandeu.ac.uk/wp-content/uploads/2021/11/Brexit-and-Services-Trade-Working-Paper.pdf