https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef1714en.pdf
http://ourglobalfuture.com/wp-content/uploads/2017/05/Global-Future-The_case_for_immigration.pdf
https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/populationestimates/articles/overviewoftheukpopulation/mar2017