http://economics.mit.edu/files/12979
https://www.esri.ie/system/files/publications/RS123.pdf
http://www.ftseglobalmarkets.com/news/uk-pension-deficits-rise-to-£145bn-liabilities-at-record-high.html
https://trade.ec.europa.eu/doclib/docs/2021/july/tradoc_159709.pdf