1. Air quality criteria and guides for urban air pollutants;World Health Organization;W.H.O. Technical Report No. 506,1972
2. Atmospheric sulfur dioxide and sulfate;Altshuller;Env. Science Technol.,1973
3. The impact of air pollutants on physiologic responses of the respiratory tract;Amdur,1970
4. Human response to controlled levels of SO2;Andersen;Arch. Env. Health,1974