1. Millman, P. M., in From Plasma to Planet (edit. by Elvius, A.) 157–168 (Wiley, New York, 1972).
2. Delsemme, A. H., in Cosmochemistry (edit. by Cameron, A. G. W.) 89–101 (Reidel, Dordrecht, 1973).
3. Schneider, F., Storzer, D., Hartung, J. B., Fechtig, H., and Gentner, W., Proc. Fourth Lunar Sci. Conf., 3, 3277–3290 (Pergamon, Oxford. 1973).
4. White, E. W., Denny, P. J., and Irving, S. M., in The Electron Microprobe (edit. by McKinley. T. D., Heindrech, K. F. J., and Wittry, D. B.) 791–804 (Wiley, New York, 1966).
5. Bavard, M., in Microprobe Analysis (edit. by Anderson, C. A.), 323–348 (Wiley, New York, 1973).