APA (7th ed.) Citation

Ewel, J. J., & Whitmore, J. L. (1973). The ecological life zones of Puerto Rico and the U.S. Virgin Islands. Institute of Tropical Forestry.

Chicago Style (17th ed.) Citation

Ewel, John J., and Jacob L. Whitmore. The Ecological Life Zones of Puerto Rico and the U.S. Virgin Islands. Rio Piedras, P.R.: Institute of Tropical Forestry, 1973.

MLA (9th ed.) Citation

Ewel, John J., and Jacob L. Whitmore. The Ecological Life Zones of Puerto Rico and the U.S. Virgin Islands. Institute of Tropical Forestry, 1973.