Other
Cbpp.org: Are State Taxes Becoming More Regressive?
This article from Center on Budget Policies and Priorities shows the correlation between state's reduction of taxes and regressive taxes.
Auburn University
Auburn University: A Glossary of Political Economy Terms: Regressive Taxes
Basic definition and examples given for what a regressive tax is.
Curated OER
Vat Theories Progressive or Regressive Who Pays What?
Explains progressive, regressive, and proportional taxes and applies them to the value added tax (VAT).