Funded by the National Science Foundation PEET program (Partnerships for Enhancing Expertise in Taxonomy)
Curtis, D., and A. Tegethoff. 1978. Intermountain Region (R-4). Pages 13-16 in H. D. Brown and P. W. Orr, Forest insect and disease conditions in the United States 1976. United States Department of Agriculture, Forest Service. vi + 40 p.