Biblio

P. Esterhuysen y Findlay, A., «The call that changed the school». Mvula Trust, Braamfontein, South Africa, p. 24 p. : ill., 1999.

A. W. Korf, Wilken, J. W., y Nel, N. J., «Strategies and management models for metropolitan wastewater, implementation and evaluation in the East Rand, South Africa», Water science and technology, pp. p. 101-108 : 3 fig., 2 tab., 1996.