Okun, D. A., & Ernst, W. R. (1987). Community piped water supply systems in developing countries: A planning manual. World Bank.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रOkun, Daniel Alexander, और Walter R. Ernst. Community Piped Water Supply Systems in Developing Countries: A Planning Manual. Washington, D.C: World Bank, 1987.
एमएलए (9वां संस्करण) प्रशस्ति पत्रOkun, Daniel Alexander, और Walter R. Ernst. Community Piped Water Supply Systems in Developing Countries: A Planning Manual. World Bank, 1987.
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