1. Bailey, R. G.: 1980, ‘Description of the ecoregions of the United States,’ USDA Forest Service Misc. Pub. 1391, 77 pp.
2. Barber, M. C. (ed.).: 1994, ‘The Environmental Monitoring and Assessment Program Indicator Development Strategy,’ EPA/620/R-94/022, U.S. Environmental Protection Agency, Office of Research and Development, EMAP-Center, Research Triangle Park, NC.
3. Blake, J. G.: 1983, ‘Trophic structure of bird communities in forest patches in east-central Illinois,’ Wilson Bulletin 95, 416–430.
4. Bradford, D. F., Franson, S. E., Neale, A. C., Heggem, D. T., Miller, G. R., and Cantebury, G.E.: (In press), ‘Bird species assemblages as indicators of biological integrity in Great Basin rangeland,’ Environmental Monitoring and Assessment.
5. Brauning, D.W. (ed.): 1992, Atlas of Breeding Birds in Pennsylvania, University of Pittsburgh Press, Pittsburgh, PA.