https://www.boeckler.de/pdf/p_imk_study_58_2018.pdf
https://www.boeckler.de/pdf/p_imk_report_139_2018.pdf
https://www.eca.europa.eu/Lists/ECADocuments/SR22_17/SR_External_consultants_EN.pdf
https://knowledge.wharton.upenn.edu/article/how-the-u-s-could-stabilize-debt-and-fuel-economic-growth/