https://ec.europa.eu/commission/sites/beta-political/files/guiding-principles-dialogue-ei-ni_en.pdf
http://www.epc.eu/documents/uploads/pub_7788_whatnowoptionsforbrexit.pdf?cmpid=BBBXT061617_BIZ&utm_medium=email&utm_source=newsletter&utm_term=170616&utm_campaign=brexit
http://cer.eu/in-the-press/speech-michel-barnier-future-eu-conference
https://publications.parliament.uk/pa/ld201719/ldselect/ldeucom/15/15.pdf