https://voxdev.org/topic/labour-markets-migration/let-their-people-come-migrants-drivers-knowledge-diffusion
https://www.crisisgroup.org/global/misery-strategy-human-cost-conflict
https://www.eurofound.europa.eu/sites/default/files/wpef17037.pdf
http://blogs.lse.ac.uk/brexit/2018/05/15/switzerland-wanted-more-immigration-controls-but-economic-self-interest-will-probably-prevail/
http://ec.europa.eu/eurostat/statistics-explained/index.php/Acquisition_of_citizenship_statistics
https://openmigration.org/en/op-ed/how-immigrants-are-saving-the-italian-economy-and-pensions/
http://www.migrationobservatory.ox.ac.uk/resources/reports/unsettled-status-which-eu-citizens-are-at-risk-of-failing-to-secure-their-rights-after-brexit/
https://cdn.tspace.gov.au/uploads/sites/107/2018/04/Shaping-a-Nation-1.pdf
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/695321/An_inspection_of_exit_checks.pdf