I. Carruthers and Stoner, R.,
Economic aspects and policy issues in groundwater development, vol. no. 496. Washington, DC, USA: World Bank, 1981, p. ii, 6, 110 p.: fig., tab.
PAHO -Washington, DC, US,
Environmental health activities of the Pan American Health Organization, vol. no. 1. Washington, DC, USA: Pan American Health Organization (PAHO), 1981, p. vi, 49 p.
H. Van and Pineo, C. S.,
“Institutional development for IEOS : Instituto Ecuatoriano de Obras Sanitarias : report”, vol. no. 12. Water and Sanitation for Health Project (WASH), Arlington, VA, USA, p. iii, 57, 3 p.: fig., tab., 1981.
S. K. Runyoro,
“Pit latrine emptying”. Loughborough University of Technology, Department of Civil Engineering, Loughborough, UK, p. viii, 94 p.: fig., tab., 1981.