https://www.socialeurope.eu/2017/06/eurozones-hidden-strength/
https://www.diw.de/documents/publikationen/73/diw_01.c.578096.de/18-7-3.pdf
https://publications.parliament.uk/pa/cm201719/cmselect/cmpubacc/1793/1793.pdf
https://www.exact.com/benl/downloads/finance/whitepaper-cijfers-altijd-het-antwoord