https://www.socialeurope.eu/2017/05/smooth-brexit-interests-germany-much-uk/
https://www.gov.uk/guidance/status-of-eu-nationals-in-the-uk-what-you-need-to-know
http://www.assemblee-nationale.fr/14/pdf/rap-info/i4551.pdf
http://www.bbc.com/news/uk-43782241