https://ec.europa.eu/commission/publications/position-paper-transmitted-eu27-governance_en
http://www.transfrontier.eu/regions/ireland-northern-ireland/
https://ukandeu.ac.uk/wp-content/uploads/2020/05/UKICE-Post-Brexit-Gov-NI-Report.pdf
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/695321/An_inspection_of_exit_checks.pdf