
https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef19036en.pdf

https://ec.europa.eu/commission/publications/agenda-19-june-meeting-between-eu-and-uk-article-50-negotiations_en

https://www.parliament.uk/documents/commons-committees/culture-media-and-sport/Background%20paper%20-%202016%20Referendum%20Expenses%20Opinion%20-%20Matrix%20Chambers.pdf