McDougall, C. (2015). Natural born heroes: Mastering the lost secrets of strength and endurance.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रMcDougall, Christopher. Natural Born Heroes: Mastering the Lost Secrets of Strength and Endurance. 2015.
एमएलए (8वां संस्करण) प्रशस्ति पत्रMcDougall, Christopher. Natural Born Heroes: Mastering the Lost Secrets of Strength and Endurance. 2015.
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