Schwartz, S. H., Spring, B., & Spring, I. (1983). Nature in the Northwest: An introduction to the natural history and ecology of the northwestern United States from the Rockies to the Pacific. Prentice-Hall.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रSchwartz, Susan H., Bob Spring, और Ira Spring. Nature in the Northwest: An Introduction to the Natural History and Ecology of the Northwestern United States from the Rockies to the Pacific. Englewood Cliffs, N.J.: Prentice-Hall, 1983.
एमएलए (8वां संस्करण) प्रशस्ति पत्रSchwartz, Susan H., et al. Nature in the Northwest: An Introduction to the Natural History and Ecology of the Northwestern United States from the Rockies to the Pacific. Prentice-Hall, 1983.
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