
https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/populationestimates/articles/overviewoftheukpopulation/mar2017

http://library.fes.de/pdf-files/id/ipa/13354.pdf

http://uk.reuters.com/article/us-britain-eu-negotiations-idUKKBN17R1XJ