Ell, T. A., Le Bihan, N., & Sangwine, S. J. (2014). Quaternion fourier transforms for signal and image processing. ISTE : Wiley.

Ell, Todd A., Nicolas Le Bihan, and Stephen J. Sangwine. Quaternion Fourier Transforms for Signal and Image Processing. London ; Hoboken, New Jersey: ISTE : Wiley, 2014.

Ell, Todd A., et al. Quaternion Fourier Transforms for Signal and Image Processing. ISTE : Wiley, 2014.