https://insightcrime.org/wp-content/uploads/2023/06/HGBF-US-Policy-OC-and-Migration-Policy-Brief-InSight-Crime-June-2023-FINAL-ENG.pdf
https://www.eurofound.europa.eu/sites/default/files/wpef17037.pdf
http://uk.reuters.com/article/uk-britain-eu-immigration-idUKKBN18L0XG