Flora of the Pacific Northwest, Hitchcock and Cronquist, University of Washington Press, 7th Printing, 1981.
Seeds:Ecology, Biogeography, and Evolution of Dormancy and Germination,Baskin and Baskin, Academic Press, 1998.
Seeds of the Woody Plants of North America, Young and Young, Dioscorides Press, 1992.
Seeding Rate Statistics for Native and Introduced Species, Hassell, N.P.S and N.R.C.S.,1996.
Glacier National Park Propagation Records, unpublished.