Freidel, F. (1982). America in the twentieth century (5th ed.). Knopf : distributed by Random House, McGraw-Hill.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रFreidel, Frank. America in the Twentieth Century. 5th ed. New York: Knopf : distributed by Random House, McGraw-Hill, 1982.
एमएलए (8वां संस्करण) प्रशस्ति पत्रFreidel, Frank. America in the Twentieth Century. 5th ed. Knopf : distributed by Random House, McGraw-Hill, 1982.
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