1. Maltoni, D., Maio, D., Jain, A.K., and Prabhakar, S.: ‘Handbook of fingerprint recognition’, (Springer Verlag, New York 2003 June), p. 286–291
2. De-noising by soft-thresholding
3. Ideal spatial adaptation by wavelet shrinkage
4. http://fpserver.cse.cuhk.edu.hk/liveness.htm