https://ec.europa.eu/commission/sites/beta-political/files/joint_report.pdf
http://www.reuters.com/article/us-britain-eu-verhofstadt-idUSKBN19V0WP
https://publications.parliament.uk/pa/cm201719/cmselect/cmexeu/935/935.pdf
http://blogactiv.eu/blog/2012/05/15/stumbling-towards-the-brexit/