Douglass, Bernard S., Gary H Sander, Oregon State University. Extension Service, Washington State University. Cooperative Extension, University of Idaho. Cooperative Extension Service, and United States. Department of Agriculture. 1982. Developing Sheared Douglas-Fir Christmas Trees [1982]. : [Corvallis, Or.] : Oregon State University Extension Service ; [Pullman, Wash.] : Washington State University Cooperative Extension ; [Moscow, Idaho] : University of Idaho Cooperative Extension System ; [Washington, D.C.] : U.S. Dept. of Agriculture.