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F. Cleaver,
«Community maintenance of handpumps». University of Zimbabwe, Department of Rural and Urban Planning, Harare, Zimbabwe, p. 147 p.: tab., fig., 1990.
B. Department BT,
«Manual on operation and maintenance of gravity flow water system». Bhutan, Department of Works and Housing, Public Health Engineering Division, Thimphu, Bhutan, p. 67 p. : drwngs, 1990.
I. D. Yayasan Di Yogyakarta, Jakarta, I. D. U. N. I. C. E. F. -, y Jakarta, I. D. National D.,
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