http://www.ips-journal.eu/in-focus/migration-and-the-european-left/article/show/turn-left-the-other-left-2179/
http://www.cbi.org.uk/index.cfm/_api/render/file/?method=inline&fileID=FC18E9C9-C854-4578-AE0D9A1C9367ABC6
https://www.swp-berlin.org/publications/products/arbeitspapiere/WP_03-2021_EPIN-Report_CoFoE_01.pdf