M. Ungureanu, J. W. M. Bergmans, M. Mischi, S. G. Oei, and R. Strungaru, “Improved method for fetal heart rate monitoring,” Proceedings of the 2005 IEEE Engineering in Medicine and Biology 27th Annual International Con-ference, Shanghai, China, pp. 5916–5919, January 2006.
 P. P. Kanjilal, S. Palit, and G. Saha, “Fetal ECG extrac-tion from single-channel maternal ECG using singular value decomposition,” IEEE Transactions on Biomedical Engineering, Vol. 44, pp. 51–59, 1997.
 K. Karlsso, H. Lilja, K. Lindecrantz, and K. G. Rosen, “Microprocessor based waveform analysis of the fetal electrocardiogram during labor,” International Journal of Gynaecol and Obstetrics, Vol. 30, No. 2, pp. 109–16, 1989.
 M. B. I. Reaz and L. S. Wie, “Adaptive linear neural net-work filter for fetal ECG extraction,” Proceedings of In-ternational Conference on Intelligent Sensing and Infor-mation Processing, Chennai, India, pp. 321–324, January 2004.
 G. Vasios, A. Prentza, D. Blana, E. Salamalekis, and P. Thomopoulos, “Classification of fetal heart rate tracings based on wavelet transform and self organizing map neu-ral networks,” Proceedings of the 23rd Annual Interna-tional conference of the IEEE, Istanbul, Turkey, Vol. 2, pp. 1633–1636, 2001.
 K. A. K. Azad, Z. M. Darus, and M. A. M. Ali, “Devel-opment of a fuzzy rule-based QRS detection algorithm for fetal and maternal heart rate monitoring,” Proceedings of the 20th Annual International Conference of the IEEE En-gineering in Medicine and Biology Society, Vol. 1, pp. 170–173, 1998.
 S. Selvan and R. Srinivasan, “A novel adaptive filtering technique for the processing of abdominal fetal electro-cardiogram using neural network,” Adaptive Systems for Signal Processing, Communications, and Control Sympo-sium 2000. (AS-SPCC), Louise, Alta., Canada, pp. 289–292, 2000.
 V. Zarzoso, A. K. Nandi, and E. Bacharakis, “Maternal and foetal ECG seperation using blind source separation methods,” IMA Journal of Mathematics Applied in Medi-cine and Biology, Vol. 14, pp. 207–225, 1997.
 F. Vrins, C. Jutten, and M. Verleysen, “Sensor array and electrode selection for non-invasive fetal electrocardio-gram extraction by independent component analysis,” Proceedings 5th International Conference Independent Component Analysis, Granada, Spain, pp. 1017–1024, 2004.