
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/uploads/system/uploads/attachment_data/file/655232/DExEU_ARA_v5.0_amended_version_14.08.17__1_.pdf

https://theconversation.com/why-the-eus-singapore-ruling-does-not-lead-to-a-smoother-brexit-road-for-britain-78116