APA (7th ed.) Citation

Bailey, R. G. (1976). Ecoregions of the United States. U.S. Forest Service.

Chicago Style (17th ed.) Citation

Bailey, Robert G. Ecoregions of the United States. [Washington]: U.S. Forest Service, 1976.

MLA (9th ed.) Citation

Bailey, Robert G. Ecoregions of the United States. U.S. Forest Service, 1976.