Childers, E. (2011). The riddle of the sands: A record of secret service. Penguin Books.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रChilders, Erskine. The Riddle of the Sands: A Record of Secret Service. New York: Penguin Books, 2011.
एमएलए (8वां संस्करण) प्रशस्ति पत्रChilders, Erskine. The Riddle of the Sands: A Record of Secret Service. Penguin Books, 2011.
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