Walker, P.

Walker, P. & Pollard, S., 2000. Catchment management and water supply and sanitation in the Sand River Catchment, South Africa : description and issues, (WHIRL Project working paper no. 1) Chatham, UK: Natural Resources Institute, University of Greenwich. Available at: https://fr.ircwash.org/sites/default/files/Pollard-2000-Catchment.pdf.