1. Birch, T.W., 1982. Private Forest-land Owners of the United States, 1978 (Res. Bul. WO-1). US Department of Agriculture, Forest Service, Washington, DC (pp. 64).
2. Birch, T.W., 1996. Private Forest-land Owners of the United States, 1994 (Res. Bul. NE-134). US Department of Agriculture, Forest Service, Radnor, PA (pp. 183).
3. Canadian Forest Service, 1995. Criteria and Indicators for the Conservation and Sustainable Management of Temperate and Boreal Forests: The Montreal Process (CFS Pamphlet). Natural Resources Canada, Hull, Quebec, pp. 27.
4. Cost, N.D., Howard, J., Mead, B., McWilliams, W.H., Smith, W.B., Van Hooser, D.D., Wharton, E.H., 1990. The Biomass Resource of the United States (Res. Bul. WO-57). US Department of Agriculture Forest Service, Washington Office, Washington, DC (pp. 18).
5. Egleston, N.H., 1886. Facts and figures in respect to the forests of the country and their consumption. In: Proceedings of the American Forestry Congress, Boston, September 1885. Judd & Detwiller Printers, Washington, DC, pp. 25–26.