http://sprc.info/wp-content/uploads/2012/07/Polish-Migrants-in-London-extending-the-stay.pdf
https://www.esri.ie/system/files/publications/WP677_0.pdf
http://ec.europa.eu/newsroom/just/item-detail.cfm?item_id=607452
https://www.etui.org/sites/default/files/2024-04/Benchmarking%20Working%20Europe%202024%20The%20ongoing%20quest%20for%20Social%20Europe_2024.pdf