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, 1958," Budget of the United States Government (January 16, 1957) : 936-945. https://fraser.stlouisfed.org/title/54/item/19011/toc/283974 , accessed on May 11, 2024.