Preston, H. A. (1970). A history of the Walla Walla District. U.S. Army, Corps of Engineers.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPreston, Howard A. A History of the Walla Walla District. Walla Walla, Wash.: U.S. Army, Corps of Engineers, 1970.
एमएलए (8वां संस्करण) प्रशस्ति पत्रPreston, Howard A. A History of the Walla Walla District. U.S. Army, Corps of Engineers, 1970.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.