Swaminathan A, Mao Y, M. Wu.  2004.  Image hashing resilient to geometric and filtering operations. Multimedia Signal Processing, 2004 IEEE 6th Workshop on. :355-358.

Wu M, Miller ML, Bloom JA, Cox IJ.  1999.  A rotation, scale and translation resilient public watermark. Acoustics, Speech, and Signal Processing, 1999. Proceedings., 1999 IEEE International Conference on. 4:2065vol.4-2065vol.4.