Byrne, Jim & McPeak, Ron. Bull Trout Population Assessment in the Columbia River Gorge : Annual Report 2000., report, February 1, 2001; (https://digital.library.unt.edu/ark:/67531/metadc742137/m1/3/: accessed December 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .