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December 2007, Water Research Commission, Pretoria, South Africa, Ring-bound soft cover, 276 pages. WRC Report No. TT 320/07; ISBN 978-1-77005-629-9; price R100.00 (South Africa), US$50.00 (international). Obtainable from the Water Research Commission, Private Bag X03, Gezina, Pretoria 0031, South Africa, or orders@wrc.org.za
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J. du G. Harrison (2009) studied this question.
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