Bowman. History of the Motorcycle Detail. Traffic Division, PortlandPoliceBureau, Portland, OR (1983, edited in 1999 by Officer Michael Clary). [2007-06-16]
Haberman, Maggie; Corasaniti, Nick; Karni, Annie. As Trump Pushes Into Portland, His Campaign Ads Turn Darker. The New York Times. 2020-07-21 [2021-04-07]
[1][永久失效連結] Portland Parks and Recreation Department. Trees by Location. City of Portland. 2012 [2013-06-18]. (原始内容存档于2013-02-15). Bureau of Environmental