Debt Limit
https://home.treasury.gov/policy-issues/financial-markets-financial-institutions-and-fiscal-service/debt-limit#:~:text=The%20debt%20limit%20is%20the,tax%20refunds%2C%20and%20other%20payments.

The Hutchins Center Explains: The debt limit
https://www.brookings.edu/blog/up-front/2019/03/15/the-hutchins-center-explains-the-debt-limit/

Debt Ceiling
https://www.investopedia.com/terms/d/debt-ceiling.asp

Q&A: Everything You Should Know About the Debt Ceiling
http://www.crfb.org/papers/qa-everything-you-should-know-about-debt-ceiling

DEBT LIMIT 101
https://www.rpc.senate.gov/policy-papers/debt-limit-101