https://policyexchange.org.uk/wp-content/uploads/2017/07/Farming_Tomorrow.pdf
http://www.assemblee-nationale.fr/14/pdf/rap-info/i4485.pdf
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/899991/200713_BPDG_-_Border_Operating_Model_FINAL_1320_edit.pdf
https://www.gov.uk/government/news/david-davis-opening-remarks-at-the-start-of-the-fourth-round-of-eu-exit-negotiations