1. American Public Health Association 1985 Standard Methods for the Examination of Water and Wastewater, 16th edn. Washington DC: APHA.
2. Association of Official Analytical Chemists 1984 Official Methods of Analysis of the Association of Official Chemists, 14th edn. Washington DC: AOAC.
3. Buchanan, R.C., Gibbons, N.E., Cowan, S.T., Holt, J.G., Liston, J., Murray, R.G.E. & Stanier, R.Y. (eds) 1974 Bergey's Manual of Determinative Bacteriology, 8th edn. Baltimore: Williams & Wilkins.
4. Cohen-Bazire, G., Sistrom, W.R. & Stanier, R.Y. 1957 Kinetic studies of pigment synthesis by non-sulfur purple bacteria. Journal of Cellular and Comparative Physiology 49, 25?68.
5. Devlin, R.M. & Barker, A.V. 1971 Photosynthesis. New Delhi: Affiliated East-West Press.