1. Physical and Chemical Characteristics of Aquatic Humus;Gjessing,1976
2. Singlet oxygen in natural waters
3. J. Carey, Canada Centre for Inland Waters, Burlington, Ontario, Canada, personal communication, 1979.
4. Humic Substances in the Environment;Schnitzer,1972
5. Soil Components, Volume 1, Organic Components;Flaig,1975