1. Wastewater Engineering: Treatment, Disposal and Reuse;Franklin,1991
2. Theory and Practice of Water and Wastewater Treatment;Droste,1997
3. Hand book of Drinking Water Quality: Standards and Controls;John,1990
4. Population and Food: Global Trends and Future Prospects;Dyson,1996
5. Theory and Practice of Water and Wastewater Treatment;Droste,1997