18-12 Authority of Tax Law Sources. Assuming that you have discovered favorable support for your position taken in a controversy with an IRS agent in each of the sources listed below, indicate how you would use these authoritative sources in your discussion with the agent.

1. A decision of the U.S. District Court having jurisdiction over your case if litigated.
2. Treasury Regulation.
3. The Internal Revenue Code.
4. A decision of the Supreme Court.
5. A decision of the Court of Appeals.
6. A decision heard under the small tax case procedures of the Tax Court.
7. A decision of the U.S. Tax Court.
8. A private letter ruling issued to another taxpayer.
9. A Revenue Ruling.
10. A tax article in a leading periodical.