1. V. N. Kuleshov and T. I. Boldyreva, in Proc. 1997 IEEE Int. Frequency Control Symp., Orlando, May 28–30, 1997 (IEEE, New York, 1997), p. 446.
2. T. I. Boldyreva, in Proc. 2001 IEEE Int. Frequency Control Symp. and PDA Exhibition, Seattle, June 8, 2001 (IEEE, New York, 2001), p. 183.
3. T. I. Boldyreva and V. N. Kuleshov, in Proc. 13th European Frequency and Time Forum and 1999 IEEE Int. Frequency Control Symp., Besancon, France, April, 1999 (IEEE, New York, 1999), p. 1184.