Pfafflin, J. R., & Ziegler, E. N. (1983). Encyclopedia of environmental science and engineering (2nd rev. and updated ed.). Gordon and Breach Science Publishers.

Pfafflin, James R., and Edward N. Ziegler. Encyclopedia of Environmental Science and Engineering. 2nd rev. and updated ed. New York: Gordon and Breach Science Publishers, 1983.

Pfafflin, James R., and Edward N. Ziegler. Encyclopedia of Environmental Science and Engineering. 2nd rev. and updated ed. Gordon and Breach Science Publishers, 1983.