United States. Office of Management and Budget. "Fiscal Year 2022 : Table 3.2 - Outlays by Function and Subfunction: 1962–2026," Historical Tables, Budget of the United States Government (May 28, 2021). https://fraser.stlouisfed.org/title/383/item/603956/content/xlsx/BUDGET-2022-TAB-4-2, accessed on April 18, 2026.
United States Government Publishing Office