1. Biological extraction of nutrients;Borchardt;J. Wat. Pollut. Control Fed.,1968
2. Parameters of phosphate removal by activated sludge;Connell,1967
3. An enzymatic technique to detect surplus phosphorus uptake by activated sludge;Fruh,1970
4. Effect of Phosphorus on the Activated Sludge Process;Greenburg;Sewage Ind. Wastes,1955