1. Long-term research on forest dynamics in the Pacific Northwest: a network of permanent forest plots;Acker,1998
2. Applegate, J.R., 2000. A comparison of techniques for estimating overstory canopy cover. Master of Science Thesis. The University of Montana, 82 pp.
3. Azuma, D.L., Hanson, E., 2002. Compilation procedures for the western Oregon inventory, 1997. Unpublished Report on file at the Portland Forestry Sciences Lab, USDA Forest Service Pacific Northwest Research Station, 620 SW Main St., Suite 400, Portland, OR, 97205, 223 pp.
4. Estimation of ground canopy density from ground measurements;Bonnor;J. For.,1967
5. Comparison of methods for estimating forest overstory cover: differences among techniques;Bunnell;Can. J. For. Res.,1990