1. Svenska vattenkvalitetskriterier;Ahl,1977
2. Water quality criteria for freshwater fish;Alabaster,1980
3. Improved sludge digestion is possible;Albertson;Water Wastes Eng,1968
4. Toxicity of trivalent chromium in the anaerobic digestion process;Alkan;Wat. Res.,1996
5. Waste water treatment mechanism in anoxic stabilisation ponds;Almasi A.;Wat. Sri. Tech.,1996