Monitoring larval populations of the Douglas-fir tussock moth and the western spruce budworm on permanent plots [electronic resource] : sampling methods and statistical properties of data / A.R. Mason and H.G. Paul.
Portland, Or. (333 S.W. First Ave., P.O. Box 3890, Portland 97208-3890) : U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station,