https://www.boeckler.de/pdf/p_imk_report_139_2018.pdf
https://www.bruegel.org/sites/default/files/2023-06/PB%2012%202023.pdf
http://www.transparency.org/news/feature/europe_and_central_asia_an_overall_stagnation
https://www.faz.net/aktuell/politik/inland/gastbeitrag-wolfgang-schaeuble-aus-eigener-staerke-16846887.html?utm_source=POLITICO.EU&utm_campaign=a80ea0a946-EMAIL_CAMPAIGN_2020_07_09_05_10&utm_medium=email&utm_term=0_10959edeb5-a80ea0a946-190380769