1. Standard Method for Specifying Color by the Munsell System;ASTM,1980
2. Ecological characterisation classification, and modelling of New Zealand rivers: an introduction and synthesis;Biggs;New Zealand Journal of Marine and Freshwater Research,1990
3. Public perception of water quality;David;Water Resources Research,1971
4. Davies-Colley, R. J., Quinn, J. M., Hickey, C. W. and Ryan, P. A. (In press). Effects of clay discharges on streams. I. Optical properties and epilithon. Hydrobiologia.
5. Measuring water clarity with a black disk;Davies-Colley;Limnology and Oceanography,1988