United States. Bureau of the Budget and United States. Office of Management and Budget. "Post Office Department," in United States. Bureau of the Budget and United States. Office of Management and Budget. "Fiscal Year Ending June 30, 1929," Budget of the United States Government (December 5, 1927) : 61-69. https://fraser.stlouisfed.org/title/54/item/18972/toc/44749 , accessed on May 11, 2024.