American Public Health Association, American Water Works Association, Water Pollution Control Federation, & Water Environment Federation. (1992). Standard methods for the examination of water and wastewater (18a. ed.). A.P.H.A.

American Public Health Association, American Water Works Association, Water Pollution Control Federation, and Water Environment Federation. Standard Methods for the Examination of Water and Wastewater. 18a. ed. Washington, D.C: A.P.H.A, 1992.

American Public Health Association, et al. Standard Methods for the Examination of Water and Wastewater. 18a. ed. A.P.H.A, 1992.