Foxon, K; Still, D (2012). Do pit additives work?. Water Research Commission, University of Kwazulu-Natal, Partners in Development (PiD), South Africa. Archived from the original on 2015-02-13. Retrieved 2016-02-28.
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Foxon, K; Still, D (2012). Do pit additives work?. Water Research Commission, University of Kwazulu-Natal, Partners in Development (PiD), South Africa. Archived from the original on 2015-02-13. Retrieved 2016-02-28.