Stevenson, R.J. and Bahls, L.L. (1999) Periphyton Protocols In: Barbour, M.T., Gerritsen, J., Snyder, B.D. and Stribling, J.B. 1999. Rapid Bioassessment Protocols for Use in Streams and Wadeable Rivers: Periphyton, Benthic Macroinvertebrates, and Fish, Second Edition, EPA 841-B-99-002. U.S. Environmental Protection Agency, Office of Water, Washington, D.C. http://water.epa.gov/scitech/monitoring/rsl/bioassessment/
