D. Veldkamp,
Recommended practices for testing water-pumping windmills, vol. no. 100. Washington, DC, USA: World Bank, 1989, p. x, 26 p.: fig.
G. A. Bridger,
Water quality and treatment, vol. no. D3. Ratmalana, Sri Lanka: National Water Supply and Drainage Board, 1989, p. iv, 182 p.: fig., tab.