1. F. Mako, A. Fisher, C. W. Roberson, N. Rostoker, and D. Tzach, inCollective Methods of Acceleration, edited by N. Rostoker and M. Reiser (Harwood Academic, New York, 1979), p. 317.
2. R. A. Mahaffey, J. A. Pasour, J. Golden, and C. A. Kapetanakos, in Ref. 1, p. 521.