Funded by the National Science Foundation PEET program (Partnerships for Enhancing Expertise in Taxonomy)
Lister, C. K., and D. B. Cahill. 1970. Central Rocky Mountain (R-2). Pages 21-23 in A. E. Landgraf, Forest insect and disease conditions in the United States, 1969. United States Department of Agriculture, Forest Service. vi + 40 p.