1. Dreisinger, R. B., and McGovern, P. C. 1970. Monitoring atmospheric sulfur dioxide and correlating its effects on crops in the Sudbury area. In Impact of Air Pollution on Vegetation Conference, S. N. Linzon, ed. Ontario Department of Energy and Resource Management, Toronto, 1970.
2. Durran, D. R, M. J. Meldgin, Mei-Kao Liu, T. Thoem, and D. Hendersen. 1979. A study of long range air pollution problems related to coal development in the Northern Great Plains. Atmos. Env 13: 1021–1037.
3. Gifford, F. A., Jr. 1974. The form of the frequency distribution of air pollution concentration. In Proceeding Symposium Statistical Aspects of Air Quality Data. Research Triangle Park, NC: EPA-650 14-74-038. U.S. Environmental Protection Agency.
4. Heagle, A. S., D. E. Body, and W. W. Heck. 1973. An open-top field chamber to assess the impact of air pollution on plants. Environ. Qual 2: 365–368.
5. Health, Education, and Welfare, Dept. of. 1970. Air Quality Criteria for Sulfur Oxides. Washington, DC: U.S. GPO.