Sellars, R. W. (1997). Preserving nature in the national parks: A history : with a new preface and epilogue. Yale University Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रSellars, Richard West. Preserving Nature in the National Parks: A History : With a New Preface and Epilogue. New Haven: Yale University Press, 1997.
एमएलए (9वां संस्करण) प्रशस्ति पत्रSellars, Richard West. Preserving Nature in the National Parks: A History : With a New Preface and Epilogue. Yale University Press, 1997.
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