https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/710147/DATA_-_FINAL.pdf
https://theconversation.com/why-the-eus-singapore-ruling-does-not-lead-to-a-smoother-brexit-road-for-britain-78116
https://ec.europa.eu/commission/sites/beta-political/files/revised_withdrawal_agreement_including_protocol_on_ireland_and_nothern_ireland.pdf