C. Myers, “Transformers condition monitoring by oil analysis,” Large or Small: Contentment or Catastrophe, Proceedings of the 1998 1st IEE/IMeChE International Conference on Power Station Maintenance-Profitability through Reliability, pp. 53–58, 1998.
 Z. Berler, A. Golubev, V. Rusov, et al, “Vibro- acoustic method of transformer clamping pressure monitoring,” Conference Record of the 2000 IEEE International Symposium on Electrical Insulation, Anaheim, CA USA, pp. 263–266, 2000.
 S. Ji, W. Liu, et al, “The application of the wavelet packet to monitor the core and winding condition of transformer based on the vibration analysis method,” Proceedings of Chinese Society for Electrical Engneering, Vol. 21, No. 12, pp. 24–27, 2001.
 S. Ji, Y. Luo, and Y. Li, “Research on extraction technique of transformer core fundamental frequency vibration based on OLCM,” IEEE Transactions on Power Delivery, Vol. 21, No. 4, pp. 1981–1988, 2006.
 N. E. Huang, Z. Shen, S. R. Long, et al, “The empirical mode decomposition and the hilbert spectrum for nonlinear and non-stationary time series analysis,” Proceedings of Royal Society of London, Series A, pp. 903–994, 1998.
 Z. Peng, P. Tse, and F. Chu, “A comparison study of improved hilbert-huang transform and wavelet transform: Application to fault diagnosis for rolling bearing,” Mechanical Systems and Signal Processing, Vol. 19, No. 5, pp. 974–988, 2005.
 L. Brechet, M. Lucas, C. Doncarli, and D. Farina, “Compression of biomedical signals with mother wavelet optimization and best-basis wavelet packet selection,” IEEE Transactions on Bio-medical Engineering, Vol. 54, No. 12, pp. 2186–2192, 2007.
 B. S. Shajeemohan, V. K. Govindan, and B. Vijilin, “A scheme for image classification and adaptive mother wavelet selection,” International Conference on Advanced Computing and Communications, pp. 308–313, 2006.