United States. Environmental Protection Agency. Region X. Pacific Northwest Region environmental quality profile. The Region.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रUnited States. Environmental Protection Agency. Region X. Pacific Northwest Region Environmental Quality Profile. Seattle, WA: The Region.
एमएलए (8वां संस्करण) प्रशस्ति पत्रUnited States. Environmental Protection Agency. Region X. Pacific Northwest Region Environmental Quality Profile. The Region.
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