https://zoe-institut.de/wp-content/uploads/2021/06/ZOE_Report_A-future-fit-recovery_FINAL.pdf
https://ec.europa.eu/info/system/files/efb_assessment_of_euro_area_fiscal_stance.pdf
https://www.boeckler.de/pdf/p_imk_report_125e_2017.pdf
https://www.nao.org.uk/wp-content/uploads/2018/01/PFI-and-PF2.pdf