[1]   H. G. Kirk et al. in Handbook of Accelerator Physics and Engineering, A. W. Chao and M. Tigner eds., section 2.4.2.1, World Scientific, 1999, page 99.

[2]   M. Borland, Summary of Equations and Methods Used in spiffe, APS/IN/LINAC/92-2, 29 June 1992.