G. A. Bridger,
“Urban water supply and sanitation”, vol. no. D2. National Water Supply and Drainage Board, Ratmalana, Sri Lanka, p. 2 vol. (various paging): fig., tab., 1989.
Z. A. University Pietermaritzburg,
“The WATSNU literature database”. University of Natal, Dep. of Economics, Pietermaritzburg, South Africa, p. 37 p., 1989.