Wignall, P. B. (2015). The worst of times: How life on earth survived eighty million years of extinctions. Princeton University Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रWignall, P. B. The Worst of Times: How Life on Earth Survived Eighty Million Years of Extinctions. Princeton: Princeton University Press, 2015.
एमएलए (8वां संस्करण) प्रशस्ति पत्रWignall, P. B. The Worst of Times: How Life on Earth Survived Eighty Million Years of Extinctions. Princeton University Press, 2015.
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