http://fedtrust.co.uk/a-chaotic-brexit-is-still-a-possibility/
https://ec.europa.eu/commission/publications/agenda-19-june-meeting-between-eu-and-uk-article-50-negotiations_en
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/502291/54284_EU_Series_No1_Web_Accessible.pdf
http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/treasury-committee/the-uks-economic-relationship-with-the-european-union/oral/72053.html