1. P. E. M. Allen, J. M. Downer, G. W. Hastings, H. W. Melville, P. Molyneux and J. R. Urwin, Nature, 177, 910 (1956).
2. S. Okamura, T. Motoyama, T. Manabe and H. Inagaki, Large radiation sources in industry, Warsaw, 1959, IAEA Vienna, Vol. I, 1960, pp. 368–73.
3. P. E. M. Allen, G. M. Burnett, J. M. Downer and H. W. Melville, Makromol. Chem., 38, 72 (1960).
4. H. Inagaki, K. Yagi, S. Saeki and S. Okamura, Chemistry of High Polymers (Japan), 17, 37 (1960).
5. Ibid. 17, 135 (1960).