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2. APHA (1985). Standard methods for the examination of water and wastewater (16th edition). Washington DC: American Public Health Association.
3. APHA (1998). Standard methods for the examination of waste and waste water (20th edition, pp. 1193). Washington DC: American Public Health Association.
4. AwesuM.O. (1980). Observations on the biology and management of the West African giant snail (Archachatina marginata). (M. Phil Dissertation). University of Ibadan, Nigeria.