https://www.bruegel.org/sites/default/files/2022-11/PC%2020%202022_4.pdf
https://www.esri.ie/system/files/publications/WP677_0.pdf
https://www.exact.com/benl/downloads/finance/whitepaper-cijfers-altijd-het-antwoord
https://www.boeckler.de/pdf/p_wsi_report_52_2019.pdf