https://rusi.org/sites/default/files/briefingpaper-france-uk-2017.pdf
http://www.lawyersforbritain.org/eu-deal-financial-liabilities.shtml
https://publications.parliament.uk/pa/cm201719/cmselect/cmbeis/379/379.pdf
https://ec.europa.eu/commission/sites/beta-political/files/guiding-principles-dialogue-ei-ni_en.pdf