1. D. Bruhwiler, in ICFA Beam Dynamics Newsletter 65, “Beam Cooling II,” Eds. Y. Zhang & W. Chou (2014).
2. S. Abeyratne et al., Eds. Y. Zhang & J. Bisognano, arXiv:1209.0757v2 (2012).
3. L. Ahrens et al., Eds. M. Farkhondeh & V. Ptitsyn (2009).
4. ICFA Beam Dynamics Newsletter 58, Sec. 4, Eds. E. Métral & W. Chou (2012).
5. G. I. Budker, Atomnaya Énergiya 22, 346 (1967).