G. P. Jones,
«Groundwater monitoring and management : proceedings of the symposium held at Dresden, German Democratic Republic (GDR) in March 1987», vol. no. 173. IAHS Press, Institute of Hydrology, Wallingford, UK, p. xii, 484 p.: fig., tab., 1990.
B. Carlsson y Drake, E.,
«Handbook for village water supply operators». Botswana, Ministry of Local Government and Lands, Unified Local Government Service, Gaborone, Botswana, p. 108 p.: ill., 1990.
L. Morin, Jost, C., y Spruijt, H. D.,
«Health benefits of water and sanitation in Rwanda»,
Water quality bulletin, pp. p. 29-35, 64: fig., tab., 1990.
G. J. G. Kok,
«The Loukkos project : water pollution and re-use in river basins in Northern Morocco»,
Land + water international : NEDECO magazine on water, transport, infrastructure and environment, pp. p. 8-11: photogr., map., 1990.