http://ftp.iza.org/dp11249.pdf
http://visegradinsight.eu/app/uploads/2019/11/EaP-2030-Trends.pdf
http://www.ftseglobalmarkets.com/news/uk-pension-deficits-rise-to-£145bn-liabilities-at-record-high.html
https://www.esri.ie/system/files/publications/SUSTAT95_0.pdf