D Duncan, . M. (1984). The desing of ventilated improved pit latrines.
Cita Chicago Style (17a ed.)D Duncan, Mara. The Desing of Ventilated Improved Pit Latrines. Washington, DC : Technology Advisory Group, World Bank, 1984.
Cita MLA (9a ed.)D Duncan, Mara. The Desing of Ventilated Improved Pit Latrines. 1984.
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