" Singh, S. The code book: The secret history of codes and code-breaking. Forth Estate Ltd.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्र" Singh, Simon". The Code Book: The Secret History of Codes and Code-breaking. Forth Estate Ltd.
एमएलए (9वां संस्करण) प्रशस्ति पत्र" Singh, Simon". The Code Book: The Secret History of Codes and Code-breaking. Forth Estate Ltd.
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