1. Standard methods for the examination of water and wastewater;APHA,1975
2. Anaerobic treatment of kinetics of palm sludge;Chin;Water Research,1981
3. Anaerobic treatment of palm oil sludge;Chin,1979
4. Ponding system for palm oil mill effluent treatment;Chooi,1984
5. Chemical composition of palm oil mill effluents;Hwang;Planter, Kuala Lumpur,1978