
https://www.kcl.ac.uk/policy-institute/assets/uk-attitudes-to-immigration-1018742pub01-115.pdf

https://ukandeu.ac.uk/increased-immigration-from-non-eu-countries-not-just-a-british-phenomenon/

http://euroefe.euractiv.es/1311_actualidad/4466026_la-ampliacion-de-la-ue-provoco-una-fuga-de-cerebros-de-este-a-oeste.html