Freidel, F. (1982). America in the twentieth century (5th ed.). Knopf : distributed by Random House, McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)Freidel, Frank. America in the Twentieth Century. 5th ed. New York: Knopf : distributed by Random House, McGraw-Hill, 1982.
Lua MLA (8ú heag.)Freidel, Frank. America in the Twentieth Century. 5th ed. Knopf : distributed by Random House, McGraw-Hill, 1982.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.