1. Blackett, P.M.S.: 1937, Proc. Roy. Soc.
159, 1.
2. Brackett, P.M.S. and Occhialini, G.P.S.: 1933, Proc. Roy. Soc. 139, 699.
3. Crussard and Leprince-Ringuet, L.: 1937a, Compt. Rend. 204, 240; 1937b, J. Phys. Rad. 8, 213.
4. Fujioka, Y.: 1973, The Biography of Hantaro Nagaoka, (ed. Yoshio Fujioka), Asahi Shinbunsha, Tokyo, pp. 584 – 595.
5. Neddermeyer, S.H. and Anderson, C.D.: 1937, Phys. Rev. 51, 884.