1. Banks, C. J., Walker, I. 1977. Sonication of activated sludge flocs and the recovery of their bacteria on solid media. Journal of General Microbiology98:363–368.
2. Crabtree, K., McCoy, E. 1967.Zoogloea ramigera Itzigsohn, identification and description. International Journal of Systematic Bacteriology17:1–10.
3. Curds, C. R. 1975. Protozoa, pp. 203–268. In: Curds, C. R., Hawkes, H. A. (eds.), Ecological aspects of used-water treatments, vol. 1. London, New York, San Francisco: Academic Press.
4. Güde, H. 1979. Grazing by protozoa as selection factor for activated sludge bacteria. Microbial Ecology5:225–237.
5. Güde, H. 1980. Growth of microbial activated sludge populations on a polysaccharide substrate in continuous culture, pp. 363–369. In: Sikyta, B., Fencl, Z., Polacek, V. (eds.), Proceedings of the 7th Symposium on Continous Cultivation of Microorganisms. Prague: Czechoslovakia Academy of Sciences.