https://publications.parliament.uk/pa/ld201719/ldselect/ldeucom/129/129.pdf
https://ukandeu.ac.uk/why-david-cameron-called-the-2016-referendum/?mc_cid=dcb6ed542c&mc_eid=815b1928ec
https://ec.europa.eu/commission/publications/agenda-19-june-meeting-between-eu-and-uk-article-50-negotiations_en