Smith, L. C. (2011). The world in 2050: Four forces shaping civilization's northern future. Dutton ; Penguin.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रSmith, Laurence C. The World in 2050: Four Forces Shaping Civilization's Northern Future. New York: Dutton ; Penguin, 2011.
एमएलए (8वां संस्करण) प्रशस्ति पत्रSmith, Laurence C. The World in 2050: Four Forces Shaping Civilization's Northern Future. Dutton ; Penguin, 2011.
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