Birdsall, S. S., & Florin, J. (1992). Outline of american geography: Regional landscapes of the united states (Fourth edition.). John Wiley.

Birdsall, Stephen S., and John Florin. Outline of American Geography: Regional Landscapes of the United States. Fourth edition. New York: John Wiley, 1992.

Birdsall, Stephen S., and John Florin. Outline of American Geography: Regional Landscapes of the United States. Fourth edition. John Wiley, 1992.