American Public Health Association, American Water Works Association, Water Pollution Control Federation, & Greenberg, A. E. (1991). Standard methods for the examination of water and wastewater: 1991 supplement to the 17th edition. American Public Health Association.

American Public Health Association, American Water Works Association, Water Pollution Control Federation, and Arnold E. Greenberg. Standard Methods for the Examination of Water and Wastewater: 1991 Supplement to the 17th Edition. Washington, D.C.: American Public Health Association, 1991.

American Public Health Association, et al. Standard Methods for the Examination of Water and Wastewater: 1991 Supplement to the 17th Edition. American Public Health Association, 1991.