1. Casadevall, T. J., Johnston, D. A., Harris, D. M., Rose, W. I.Jr., Malinconico, L. L., Stoiber, R. E., Bornhorst, T. J., Williams, S. N., Woodruff, L. and Thompson, J. M., (1981), SO2 emission rates at Mount St. Helens from March 29 through December, 1980, U.S. Geol. Surv. Prof. Paper 1250, 193?200.
2. Casadevall, T. J., Rose, W. I., Fuller, W. H., Hunt, W. H., Hart, M. A., Moyers, J. L., Woods, D. C., Chuan, R. L. and Friend, J. P., 1984, Sulfur dioxide and particles in volcanic plumes from Poás, Arenal and Colima volcanoes, Costa Rica and Mexico, J. Geophys. Res. 89, 9633?9641.
3. Chuan, R. L., 1975, Fine Particles: Aerosol Generation, Measurement, Sampling and Analysis, B. Y. H. Liu (ed.), pp. 763?775. Academic Press, New York.
4. Chuan, R. L., Woods, D. C. and McCormick, M. P., 1981, Characterization of aerosos from eruptions of Mount St. Helens, Science 211, 830?832.
5. Delmas, R. J., Briat, M. and Legrand, M., 1982, Chemistry of south polar snow, J. Geophys. Res. 87, 4314?18.