https://theconversation.com/eu-citizens-proposal-a-lawyer-examines-the-detail-80111
https://www.esri.ie/system/files/publications/SUSTAT117.pdf
https://blogs.lse.ac.uk/brexit/2019/10/23/long-read-the-makings-of-brexit-and-the-road-ahead/
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/725288/The_future_relationship_between_the_United_Kingdom_and_the_European_Union.pdf