https://www.llri.lt/wp-content/uploads/2018/06/Labour-Migration_3.pdf
https://www.ccomptes.fr/system/files/2019-07/20190716-rapport-regimes-speciaux-retraite.pdf
http://www.ftseglobalmarkets.com/news/uk-pension-deficits-rise-to-£145bn-liabilities-at-record-high.html
https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef1663en.pdf