https://socialeurope.eu/the-left-must-embrace-fiscal-restructuring
https://www.imk-boeckler.de/download-proxy-for-faust/download-pdf?url=http%3A%2F%2F217.89.182.78%3A451%2Fabfrage_digi.fau%2Fp_imk_pb_98_2020.pdf%3Fprj%3Dhbs-abfrage%26ab_dm%3D1%26ab_zeig%3D9110%26ab_diginr%3D8482
https://www.fraserinstitute.org/sites/default/files/economic-freedom-of-the-world-2021.pdf
http://www.cesifo-group.de/portal/page/portal/DocBase_Service/studien/Studie-2017-Felbermayr-etal-Brexit-79843.pdf