https://www.sbs.strath.ac.uk/economics/fraser/20171129/GMB-Brexit-report.pdf
https://rusi.org/sites/default/files/newsbrief_37.3_elliott.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://ec.europa.eu/commission/publications/position-paper-transmitted-eu27-ongoing-police-and-judicial-cooperation-criminal-matters_en