1. B.B. Cunningham et al., Phys. Rev. 72, 739 (1947)
2. B.G. Harvey, Spallation, in Chapter 3 in Progress in Nuclear Physics, ed. by O.R. Frisch, vol. 7 (Pergamon Press, Oxford, 1959), p. 90
3. R. Serber, Phys. Rev. 72, 1114 (1947)
4. O. Kofoed-Hansen, K.O. Nielsen, Phys. Rev. 82, 96 (1951)
5. R.H. Goeckermann, I. Perlman, Phys. Rev. 76, 628 (1949)