United States. Technical Committee on Industrial Classification & United States. Bureau of the Budget. Office of Statistical Standards. (1957). Standard industrial classification manual. Executive Office of the President, Bureau of the Budget.
Lua i Stíl Chicago (17ú heag.)United States. Technical Committee on Industrial Classification agus United States. Bureau of the Budget. Office of Statistical Standards. Standard Industrial Classification Manual. Washington, D.C.: Executive Office of the President, Bureau of the Budget, 1957.
Lua MLA (9ú heag.)United States. Technical Committee on Industrial Classification agus United States. Bureau of the Budget. Office of Statistical Standards. Standard Industrial Classification Manual. Executive Office of the President, Bureau of the Budget, 1957.