https://www.publications.parliament.uk/pa/ld201617/ldselect/ldeucom/169/169.pdf
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
https://publications.parliament.uk/pa/cm201719/cmselect/cmhaff/421/421.pdf