https://www.sbs.strath.ac.uk/economics/fraser/20170322/FEC-Vol41-No1.pdf
https://www.esri.ie/system/files/publications/WP677_0.pdf
https://www.aspistrategist.org.au/the-eu-needs-fiscal-union/
https://www.ecb.europa.eu/pub/pdf/ecbu/eb201703.en.pdf?ea7747ab0ef3b038300a8d51a3a95313