Langer, W. L. (1952). An encyclopedia of world history: Ancient, medieval, and modern, chronologically arranged (Revised edition.). Houghton Mifflin.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रLanger, William L. An Encyclopedia of World History: Ancient, Medieval, and Modern, Chronologically Arranged. Revised edition. Boston: Houghton Mifflin, 1952.
एमएलए (8वां संस्करण) प्रशस्ति पत्रLanger, William L. An Encyclopedia of World History: Ancient, Medieval, and Modern, Chronologically Arranged. Revised edition. Houghton Mifflin, 1952.
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