1. Standard Methods for the Examination of Water and Wastewater;APHA,1989
2. Advanced biological treatment to achieve nutrient removal;Burdick;J. Wat. Pollut. Control Fed.,1982
3. Settling velocity model of activated sludge;Cho;Wat. Res.,1993
4. Nitrification and denitrification in wastewater treatment;Christensen,1978
5. Respiration and denitrification studies on laboratory and works activated sludges;Clayfield;Wat. Pollut. Control,1974