- History of taxation in the United States.
- Tariff in United States history.
- Income tax in the United States.
- Internal Revenue Service.
- Commissioner of Internal Revenue.
- Revenue Act of 1861.
- Revenue Act of 1862.
- Wilson-Gorman Tariff of 1894.
- Pollock v. Farmers' Loan & Trust Co. (1895)
- Sixteenth Amendment to the United States Constitution.
- - Case law.
- Revenue Act of 1913.
- Brushaber v. Union Pacific Railroad Co.
- Marginal tax rates.
- Effective income tax rates.