https://www.ipg-journal.de/regionen/europa/artikel/detail/wind-in-ihren-segeln-4625/
http://oegfe.at/wordpress/2017/05/the-free-movement-of-workers-within-the-eu-and-the-case-of-austria-balancing-distortions-and-adding-value-op-ed-paul-schmidt-the-european-financial-review/
https://www.epp.eu/files/uploads/2017/04/11-EPP-Resolution-1-2.pdf
https://www.migrationpolicy.org/article/spain-immigration-system-evolution?eType=EmailBlastContent&eId=a1fcdaaa-93ef-4a35-9397-e325534c6592&mc_cid=e4eef57c9d&mc_eid=d10a99d01e