https://www.sachverstaendigenrat-wirtschaft.de/fileadmin/dateiablage/gutachten/jg201819/Chapter_1.pdf
https://www.europarl.europa.eu/at-your-service/files/be-heard/eurobarometer/2019/parlemeter-2019/executive-summary/en-parlemeter-2019-executive-summary.pdf
http://www.votewatch.eu/blog/alliances-matter-political-networks-the-rule-of-law-principles-and-the-split-of-eu-money-mff/