M. Chaudhuri and Gupta, A.,
“Domestic water purification for developing countries”,
Aqua : journal of water supply research and technology, pp. p. 290-298: 8 fig., 5 tab., 1992.
V. M. L. Heidweiller,
“Fluoride removal methods”, in
Endemic fluorosis in developing countries : causes, effects and possible solutions : report of a symposium held in Delft, The Netherlands, April 27th, 1990, 1992, pp. p. 51-85 : 5 fig., 7 tab.