United States. Forest Service. Pacific Northwest Region. (2000). Columbia River Gorge National Scenic Area. The Service.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रUnited States. Forest Service. Pacific Northwest Region. Columbia River Gorge National Scenic Area. Hood River, OR: The Service, 2000.
एमएलए (8वां संस्करण) प्रशस्ति पत्रUnited States. Forest Service. Pacific Northwest Region. Columbia River Gorge National Scenic Area. The Service, 2000.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.