https://www.socialeurope.eu/the-final-countdown-the-eu-poland-and-the-rule-of-law
https://www.cgdev.org/blog/beyond-brexit-end-eu-uk-free-movement-should-reset-debate-uk-migration-policy
https://cerre.eu/wp-content/uploads/2024/01/CERRE.BOOK_.DMA_.17JAN.pdf
http://www.economics-ejournal.org/economics/journalarticles/2017-18