Não informado. (1963). US Forest Service Research Paper PSW. U.S. Forest Service.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. US Forest Service Research Paper PSW. Berkeley, Calif: U.S. Forest Service, 1963.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. US Forest Service Research Paper PSW. U.S. Forest Service, 1963.
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