L. K. National W. Ratmalana,
Ground water, vol. no. D4. Ratmalana, Sri Lanka: National Water Supply and Drainage Board, 1988, p. ii, 53 p.: fig.
R. Stark,
“Well construction manual”. Sarvodaya Rural Technical Services, Moratuwa, Sri Lanka, p. 26 p.: fig., 1988.
M. Nagorski and Pineo, C.,
“A workshop design for well improvement : protecting open wells”. Water and Sanitation for Health Project (WASH), Arlington, VA, USA, p. 243 p.: fig., 1988.