1. Van Deusen, B. D. A Statistical Technique for the Dynamic Analysis of Vehicles Traversing Rough Yielding and Non-yielding Surfaces (NASA Rep. No. CR-659, 1967).
2. Thomas, T. R. & Sayles, R. S. Trans. Am. Soc. mech. Engrs, Paper 76-WA/ Prod-23 (1976).
3. Thomas, T. R. & Sayles, R. S. Proc. I. Mech. E., Tribology 1976 Conf., University of Durham (1976).
4. Gray, G. G. & Johnson, K. L. J. Sound Vibrat. 22, 323–342 (1972).
5. Whitehouse, D. J. & Archad, J. F. Proc. R. Soc. A316, 97–121 (1970).