R. Zimba,
«Performance evaluation of selected waste stabilization ponds in Zambia», vol. no. 21. Tampere University of Technology, Tampere, Finland, p. 113 p.: fig., tab., 1986.
R. McGowan y Hodgkin, J.,
«Water pump fieldtests in Botswana». Associates in Rural Development, Burlington, VT, USA, p. ii, 96 p.: fig., 1986.