https://www.ecb.europa.eu/pub/pdf/ecbu/eb201703.en.pdf?ea7747ab0ef3b038300a8d51a3a95313
http://eurodad.org/files/pdf/58d39b90e6546.pdf
https://www.brookings.edu/blog/up-front/2017/08/03/the-hutchins-center-explains-the-debt-limit/?utm_campaign=Brookings%20Brief&utm_source=hs_email&utm_medium=email&utm_content=54989469
https://www.ecb.europa.eu/press/key/date/2012/html/sp120726.en.html