https://www.esri.ie/system/files/publications/SUSTAT95_0.pdf
http://library.fes.de/pdf-files/iez/13375.pdf
http://blogs.lse.ac.uk/europpblog/2018/04/06/a-global-agenda-for-labour/
https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef20001en.pdf