Collins. Nature's Aristocracy. University of Nebraska Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रCollins. Nature's Aristocracy. University of Nebraska Press.
एमएलए (8वां संस्करण) प्रशस्ति पत्रCollins. Nature's Aristocracy. University of Nebraska Press.
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