United States. Bureau of the Budget and United States. Office of Management and Budget. "Analysis of Receipts by Source," in United States. Bureau of the Budget and United States. Office of Management and Budget. "Fiscal Year Ending June 30, 1967," Budget of the United States Government (January 24, 1966) : 52-64. https://fraser.stlouisfed.org/title/54/item/19020/toc/265616 , accessed on April 19, 2024.