1. Report on the Problems of Distortion in Nuclear Emulsions and Spurious Scattering Measurements at High Energies (Copenhagen, Oct. 1960).
2. E. Dahl-Jensen, M. Gailloud, W. O. Lock andG. Vanderhaeghe (1961),Il Nuovo Cimento, in press.
3. P. H. Fowler:Phil. Mag.,41, 169 (1950).
4. J. K. Bøggild andM. Scharff:Suppl. Nuovo Cimento,12, 374 (1954).
5. C. P. Powell, P. H. Fowler andD. H. Perkins:The Study of Elementary Particles by the Photographic Method (London, 1959), p. 114.