1. Bach, W. (1970): An urban circulation model. Arch. Met. Geoph. Biokl., Ser. B, 18, 155-168.
2. Black, C. and Dams, R. (1976): Study of flyy ash emission during combustion of coal. Environ. Sci. Tech., 10, 1011-1017.
3. Kellogg, W. W., Cadle, R. D., Allen, E. R., Lazrus, A. L. and Martell, E. A. (1972): The sulfur cycle. Science, 175, 587-596.
4. Magono, C., Kikuchi, K., Lee, S., Endo, T. and Kasai, T. (1965): An observation of snow crystals and their mother cloud. Jour. Eac. Sci., Hokkaido Univ., Ser. VII, 2, 123-148.
5. Magono, C., Kikuchi, K., Kimura, T., Tazawa, S. and Kasai, T. (1966): A study on the snowfall in the winter monsoon season in Hokkaido with special reference to low land snowfall. Jour. Fac. Sci., Hokkaido Univ., Ser. VII, 3,. 287-308.