http://www.lawsociety.org.uk/news/stories/leaving-in-an-orderly-fashion-our-approach-to-brexit/
https://uk.reuters.com/article/uk-britain-eu-options/stairway-to-brexit-barnier-maps-out-uks-canadian-path-idUKKBN1ED23R
https://publications.parliament.uk/pa/cm201719/cmselect/cmfaff/932/932.pdf
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/640485/Technical_note_on_Functionality_and_Protocol_7.pdf