1. M. P. Ansell, Canadian Patent 1 166942 (1984).
2. G. D. Small, PhD thesis, University of Bath, England (1984).
3. G. D. Small andM. P. Ansell, in preparation.
4. A. P. Coppa,Machine Design 28 (1968) 130.
5. A. A. Ezra andR. J. Fay, in Proceedings of Symposium on Dynamic Response of Structures, Stanford University, June 1971 (Pergamon, New York, 1972) p. 225.