1. R. A. MEYERS, Coal Desulfurization, Marcel Dekker Inc., New York (1977) p. 4.
2. S. F. SINGER (Ed.), Global Effects of Environmental Pollution, Springer-Verlag Inc., New York (1970) p. 54.
3. Air Quality Criteria for Sulfur Oxides, National Air Pollution Control Administration Publication no. Ap-50. U. S. Department of Health, Education and Welfare, Washington, Jan. 1970.
4. U. S. Environmental Protection Agency, Federal Register, 36, 24876, 1973.
5. T. D. WHEELOCK, Coal Desulfurization, American Chemistry Society Symposium Series, Washington, 1977.