Cunningham, W. P., & Cunningham, M. A. (2006). Principles of environmental science: Inquiry and applications (3rd ed.). McGraw-Hill.

Cunningham, William P., and Mary Ann Cunningham. Principles of Environmental Science: Inquiry and Applications. 3rd ed. Dubuque, IA: McGraw-Hill, 2006.

Cunningham, William P., and Mary Ann Cunningham. Principles of Environmental Science: Inquiry and Applications. 3rd ed. McGraw-Hill, 2006.