1. and 1986. Random Data: Analysis and Measurement Procedures 2nd edition, New York: Wiley.
2. and 1993. Engineering Applications and Correlation and Spectral Analysis 2nd edition, New York: John Wiley.
3. Non-linear system vibration analysis using Hilbert transform--II. Forced vibration analysis method 'Forcevib'
4. and 1987. The use of envelope and instantaneous phase methods for the response of oscillatory non-linear systems to transients. Proceedings of the 5th IMAC, London: 1460-1466.