Clayton, J. (2019). Natural rivals: John Muir, Gifford Pinchot, and the creation of America's public lands (First Pegasus books cloth edition.). Pegasus Books.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रClayton, John. Natural Rivals: John Muir, Gifford Pinchot, and the Creation of America's Public Lands. First Pegasus books cloth edition. New York: Pegasus Books, 2019.
एमएलए (8वां संस्करण) प्रशस्ति पत्रClayton, John. Natural Rivals: John Muir, Gifford Pinchot, and the Creation of America's Public Lands. First Pegasus books cloth edition. Pegasus Books, 2019.
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