https://www.boeckler.de/pdf/p_imk_study_55_2017.pdf
https://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.38.3.89
https://www.socialeurope.eu/ecb-president-lagarde-has-she-become-unstoppable
https://www.brookings.edu/articles/the-difference-in-how-the-wealthy-make-money-and-pay-taxes/