1. A combined pollution index for measurement of total air pollution;Babcock;JAPCA,1970
2. An Overview of Environmental Indicators: State of the Art and Perspectives;Bakkes,1994
3. Relation between physico-chemical and biotic indices of water and air quality;Bello,1990
4. Air pollution index and interpretation of measurements of toxic pollutant concentrations;Bezuglaya;Atmospheric Environment,1993
5. Air Pollution in the UK: 1995,1997