25. Secondary sources of authority such as tax services, citators, and legal periodicals are references that explain and comment on primary sources of authority. True False 26. The authority of the U.S. government to raise revenue through a federal income tax is derived from: a. The Internal Revenue Service. b. Eisner v. Macomber (a Supreme Court case) c. The 16th Amendment to the Constitution. d. The House Ways and Means Committee. 27. Which of the following statements regarding Revenue Rulings is correct? a. Revenue Rulings present judicial interpretations of tax law. b. Revenue Rulings present administrative interpretations of tax law. c. Revenue Rulings have the same authoritative weight as Treasury Regulations. d. The legal citation for a Revenue Ruling refers to the associated Internal Revenue Code section. 28. Which of the following sources of tax law are cross-referenced to related Internal Revenue Code sections through the use of a similar numbering system? a. Revenue Rulings b. Tax Court cases c. Treasury Regulations d. Determination Letters