1. Bailey RG (1994) Ecoregions of the United States map). Rev ed. Scale 1:7, 500,000, colored. USDA Forest Service, Washington, DC.
2. Birch TW (1996) Private Forest-Land Owners of the Northern United States, 1994. Resour Bull NE-136. USDA Forest Service, Northeastern Forest Experiment Station, Radnor, PA.
3. Birch TW, Gansner DA, Arner SL, Widmann RH (1992) Cutting activity on West Virginia timberlands. North J Appl For 9(4): 146–148.
4. Birdsey RA, Heath LS (1995) Carbon changes in U.S. forests. In: Joyce LA (ed) Productivity of America’s Forests and Climate Change. Gen Tech Rep RM-271. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Ft Collins, CO, pp 56–70.
5. Blewett MB, Potzger JE (1950) The forest primeval of Marion and Johnson Counties, Indiana, in 1819. Butler Univ Bot Stud 10:40–52.