1. Allen, S. E., H. M. Grimshaw, J. A. Parkinson & C. Quarmby, 1974. Chemical analysis of ecological materials. Blackwell Scientific Publications, Oxford.
2. Allenby, K. G., 1980. Some analysis of aquatic plants and their waters. Hydrobiologia 77: 177?189.
3. Barbieri, R., F. A. Esteves & J. W. Reid, 1984. Contribution of two aquatic macrophytes to the nutrient budget of Lobo Reservoir, Sao Paulo, Brazil. Verh. int. Limnol. 22: 1631?1635.
4. Best, E. P. H. & A. K. van der Werf, 1986. Respiration in relation to reverse substance in the submerged macrophyte Ceratophyllum demersum. L. Aquat. Bot. 26: 235?246.
5. Boyd, C. E., 1969. Production, mineral nutrient absorption, and biochemical assimilation by Justicia americana and Alternanthera philoxeroides. Arch. Hydrobiol. 66: 139?160.