http://fedtrust.co.uk/views-from-the-federal-trust/free-movement-and-migration/
http://www.europarl.europa.eu/RegData/etudes/STUD/2017/602028/IPOL_STU(2017)602028_EN.pdf
http://www.msn.com/en-gb/news/uknews/ftse-100-chiefs%e2%80%99-fury-at-no-10-letter-backing-ministers-on-brexit/ar-AArpKuh
https://www.eca.europa.eu/ECAPublications/SR-2024-06/SR-2024-06_EN.pdf