https://www.wto.org/english/res_e/booksp_e/anrep_e/anrep17_e.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://institute.global/news/customs-and-exiting-european-union