https://www.ips-journal.eu/interviews/theres-a-broad-consensus-in-denmark-around-migration-7635/
http://ec.europa.eu/eurostat/statistics-explained/index.php/Acquisition_of_citizenship_statistics
https://www.brookings.edu/blog/order-from-chaos/2018/01/25/in-rethinking-refuge-draw-lessons-from-turkey/?utm_campaign=Brookings%20Brief&utm_source=hs_email&utm_medium=email&utm_content=60257046
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/