https://www.publications.parliament.uk/pa/cm201617/cmselect/cmbeis/909/909.pdf
http://www.britishchambers.org.uk/press-office/press-releases/bcc-open-letter-to-pm-businesses-need-clarity-on-brexit.html
https://www.gov.uk/government/news/programme-for-fourth-round-of-uk-eu-article-50-negotiations
https://curia.europa.eu/jcms/upload/docs/application/pdf/2018-12/cp180187en.pdf