UNDP -New York, NY, US,
«Consultation mondiale sur l'eau salubre et l'assainissement pour les annes 90, New Delhi, Inde, 10-14 septembre 1990 : document de reference», presented at the 1990-01-01, New York, NY, USA, 1990, p. x, 97 p.: fig.
C. de Jong-Boon,
«Environmental problems in Sudan : a reader». Institute of Social Studies, Research and Project Office, The Hague, The Netherlands, p. 2 vol. (xxi, 819 p.): fig., map, tab., 1990.
World Bank -Washington, DC, US y Luxembourg, L. U. European I.,
The environmental program for the Mediterranean : preserving a shared heritage and managing a common resource. Washington, DC, USA: World Bank, 1990, p. ix, 93 p.: box, map, tab.
L. Vincent,
«Environmentally sound irrigation projects»,
Waterlines, an international journal of water, sanitation and waste, pp. p. 3-6: photogr., tab., 1990.
UNDP -New York, NY, US,
«Global consultation on safe water and sanitation for the 1990s, New Delhi, India, September 10-14, 1990 : background paper», presented at the 1990-01-01, New York, NY, USA, 1990, p. x, 52 p.: fig.
O. Linden,
«Human impact on tropical coastal zones»,
Nature and resources, pp. p. 3-11: photogr., 1990.
UNDP -New York, NY, US, World Resources Institute -Washington, DC, US, y Nairobi, K. E. U. N. E. P. -,
World resources 1990-91. New York, NY, USA: Oxford University Press, 1990, p. xiv, 383 p.: tab.