1. Bacterial and viral analysis of water and waste water;SCARPINO,1971
2. CHANG, S. L. Pathogenic free-living amoebae and recreational waters. Proc. 6th int. Conf. Wat. Pollut. Res., Jerusalem, (1972), p. 85.
3. GELDREICH, E. E., and CLARKE, N. A. The coliform test: a criterion for the viral safety of water. Proc. 13th Wat. Qual. Conf., Univ. Illinois, Urbana, (1971), p. 103.
4. The detection of enteric viruses in the water environment;SHUVAL,1972
5. Coliforms are an inadequate index of water quality;DUTKA;J. envir. Hlth,1973