APA (7th ed.) Citation

Bailey, R. G., & Kirtley, M. (1989). Ecoregions of the continents. U.S. Department of Agriculture, Forest Service.

Chicago Style (17th ed.) Citation

Bailey, Robert G., and Michael Kirtley. Ecoregions of the Continents. Washington: U.S. Department of Agriculture, Forest Service, 1989.

MLA (9th ed.) Citation

Bailey, Robert G., and Michael Kirtley. Ecoregions of the Continents. U.S. Department of Agriculture, Forest Service, 1989.