• Internal Revenue Code
• Treasury Regulations
• Revenue Procedures
• Revenue Rulings
• Internal Revenue Bulletin
• Actions on Decisions
• United States Tax Court Decisions
• U.S. Supreme Court Decisions
• California Revenue & Taxation Code
• California Sales & Use Tax Regulations
• California Sales & Use Tax Annotated Opinions
• California City & County Sales and Use Tax Rates

Tax History and Tax Related Information

• History of U.S. Taxation by the U.S. Department of Treasury
• Taxation in the United States by Wikipedia
• Tax Almanac