Richberg, D. R. (1957). Labor union monopoly: A clear and present danger / by Donald R. Richberg (2. print.). Regnery.
Lua i Stíl Chicago (17ú heag.)Richberg, Donald Randall. Labor Union Monopoly: A Clear and Present Danger / by Donald R. Richberg. 2. print. Chicago: Regnery, 1957.
Lua MLA (8ú heag.)Richberg, Donald Randall. Labor Union Monopoly: A Clear and Present Danger / by Donald R. Richberg. 2. print. Regnery, 1957.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.