Riggs, R., Tiedemann, A., Cook, J., Ballard, T., Edgerton, P., Vavra, M., Krueger, W., Hall, F., Bryant, L., Irwin, L., & Delcurto, T. (2000). Modification of Mixed-Conifer Forests by Ruminant Herbivores in the Blue Mountains Ecological Province. : Portland, Or. : U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station.