Nelson, L. H. (1976). A century of Oregon covered bridges, 1851-1952: A history of Oregon covered bridges, their beginnings, development and decline, together with some mention of the builders and techniques : illustrated with old views and the author's own photographs. Oregon Historical Society.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNelson, Lee H. A Century of Oregon Covered Bridges, 1851-1952: A History of Oregon Covered Bridges, Their Beginnings, Development and Decline, Together with Some Mention of the Builders and Techniques : Illustrated with Old Views and the Author's Own Photographs. Portland: Oregon Historical Society, 1976.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNelson, Lee H. A Century of Oregon Covered Bridges, 1851-1952: A History of Oregon Covered Bridges, Their Beginnings, Development and Decline, Together with Some Mention of the Builders and Techniques : Illustrated with Old Views and the Author's Own Photographs. Oregon Historical Society, 1976.