http://www.icaew.com/-/media/corporate/files/technical/economy/brexit/eu-exit-charge.ashx
https://www.instituteforgovernment.org.uk/sites/default/files/publications/5704%20IFG%20-%20Frictionless%20Trade%20Web.pdf
https://www.esri.ie/system/files/publications/SUSTAT117.pdf
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/899991/200713_BPDG_-_Border_Operating_Model_FINAL_1320_edit.pdf