ROBERT FREDERICK. (2005). SEVEN WONDERS OF THE WORLD. REALLY USEFUL MAP COMPANY LTD.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रROBERT FREDERICK. SEVEN WONDERS OF THE WORLD. ENGLAND: REALLY USEFUL MAP COMPANY LTD, 2005.
एमएलए (9वां संस्करण) प्रशस्ति पत्रROBERT FREDERICK. SEVEN WONDERS OF THE WORLD. REALLY USEFUL MAP COMPANY LTD, 2005.
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