1. Rediske, J. H., and Hungate, F. P., Proc. Internat. Conf. Peaceful Uses Atomic Energy, 13, 354 (1955).
2. Klechkovsky, V. M. (ed.), Acad. Sci. U.S.S.R. (A.E.C.-Tr-2867) (1957).
3. Pendleton, R. C., and Hanson, W. C., Proc. Second Internat. Conf. Peaceful Uses Atomic Energy, 18, 419 (1958).
4. Fredriksson, L., Eriksson, B., Rasmuson, B., Gahne, B., Edvarson, K., and Löw, K., Proc. Second Internat. Conf. Peaceful Uses Atomic Energy, 18, 449 (1958).
5. Emerson, F., Bot. Gaz., 72, 359 (1921).