Indicate whether the following tax sources are a "Primary" source, "Secondary" source, "Both", or "Neither".

a. Sixteenth Amendment to the Constitution Primary b. Tax treaty between the United States and China Primary Temporary Regulations (issued 2014) Primary c. d. Revenue Procedure Primary General counsel memorandum (1988) Secondary e. f. Tax Court Memorandum decision Primary g. Harvard Law Review article Secondary h. Legislative Regulations Primary i. Letter ruling (before 1991) Both j. Fifth Circuit Court of Appeals decision Primary k. Small Cases Division of U.S. Tax Court decision Secondary 1. Senate Finance Committee Report Primary m. Technical advice memorandum (1993) Secondary Proposed Regulations Secondary n.